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Disclosed is an apparatus for transmitting a broadcast signal including:
an input formatter module configured to de-multiplex an input stream into
at least one data pipe (DP); a BICM module configured to perform error
correction on data of the at least one DP; a frame building module
configured to generate a signal frame including the data of the DP; and
an OFDM generation module configured to generate a transmission signal by
inserting a preamble into the signal frame and performing OFDM modulation
thereon.

This application claims priority to Provisional Application No.
61/939,280 filed on 13 Feb., 2014 in US, the entire contents of which is
hereby incorporated by reference in its entirety.

Claims

What is claimed is:

1. An apparatus for transmitting a broadcast signal, the apparatus comprising: an input formatter module configured to de-multiplex an input stream into at least one data
pipe (DP); a Bit Interleaved Coding and Modulation (BICM) module configured to perform error correction on data of the at least one DP; a frame building module configured to generate a signal frame including the data of the at least one DP; and an
Orthogonal Frequency Division Multiplexing (OFDM)) generation module configured to generate a transmission signal by inserting a preamble into the signal frame and performing OFDM modulation, wherein the input formatter module comprises: a header
compression module configured to compress Internet Protocol (IP) headers of IP packets included in an IP stream into a full header or a partial header when the input stream is the IP stream; a baseband (BB) frame slicer module configured to allocate
data of the IP packets to a BB frame; and a BB frame header insertion module configured to insert a BB frame header into the BB frame, the BB frame header including IP header compression information, wherein the IP header compression information
includes IP packet type information and IP packet position information for the IP packets, wherein the IP packet position information indicates a position of each of the IP packets within the BB frame and the IP packet type information indicates whether
each of the IP packets includes the full header or the partial header.

2. The apparatus of claim 1, wherein the IP packet position information is inserted instead of length information in each of the IP headers.

3. The apparatus of claim 1, wherein the IP packet position information is start position information of the IP packets within the signal frame or length information of the IP packets within the signal frame.

4. The apparatus of claim 1, wherein the IP header compression information is included in an extension field of the BB frame header.

5. A method for transmitting a broadcast signal, the method comprising: an input formatting operation of de-multiplexing an input stream into at least one data pipe (DP); BICM processing operation of performing error correction on data of the
at least one DF; a frame building operation of generating a signal frame including the data of the at least one DP; and an OFDM generating operation of generating a transmission signal by inserting a preamble into the signal frame and performing
Orthogonal Frequency Division Multiplexing (OFDM) modulation, wherein the input formatting operation of de-multiplexing comprises: compressing Internet Protocol (IP) headers of IP packets included in an IP stream into a full header or a partial header
when the input stream is the IP stream; allocating data of the IP packets to a baseband (BB) frame; and inserting a BB frame header including IP header compression information into the BB frame, wherein the IP header compression information includes IP
packet type information and IP packet position information for the IP packets, wherein the IP packet position information indicates a position of each of the IP packets within the BB frame and the IP packet type information indicates whether each of the
IP packets includes the full header or the partial header.

6. The method of claim 5, wherein the IP packet position information is inserted instead of length information in each of the IP headers.

7. The method of claim 5, wherein the IP packet position information is start position information of the IP packets within the signal frame or length information of the IP packets within the signal frame.

8. The method of claim 5, wherein the IP header compression information is included in an extension field of the BB frame header.

9. An apparatus for receiving a broadcast signal, the apparatus comprising: a synchronization/demodulation module configured to perform signal detection and Orthogonal Frequency Division Multiplexing (OFDM) demodulation on a received broadcast
signal; a frame parsing module configured to parse a signal frame of the broadcast signal to extract service data; a demapping/decoding module configured to convert an input signal into a bit domain and perform deinterleaving on the bit domain; and an
output processing module configured to receive the service data and output a data stream, wherein the output processing module comprises: a baseband (BB) frame header parser module configured to parse a BB frame header to obtain Internet Protocol (IP)
header compression information; a header de-compression module configured to de-compress headers of IP packets included in a BB frame by using the IP header compression information; and a packet recombining module configured to combine the IP packets
to output an IP stream, wherein the IP header compression information includes IP packet type information and IP packet position information for the IP packets, wherein the IP packet position information indicates a position of each of the IP packets
within the BB frame and the IP packet type information indicates whether each of the IP packets includes a full header or a partial header.

10. The apparatus of claim 9, wherein the IP packet position information is start position information of the IP packets within the signal frame or length information of the IP packets within the signal frame.

11. The apparatus of claim 9, wherein the IP header compression information is included in an extension field of the BB frame header.

12. A method for receiving a broadcast signal, the method comprising: a synchronization/demodulation operation of-performing signal detection and Orthogonal Frequency Division Multiplexing (OFDM) demodulation on a reception broadcast signal; a
frame parsing operation of parsing a signal frame of the reception broadcast signal to extract service data; a demapoping/decoding operation converting an input signal into a bit domain and performing deinterleaving on the bit domain; and an output
processing operating of receiving the service data and outputting a data stream, wherein the output processing operation of receiving the service data and outputting the data stream comprises: a baseband (BB) frame header parsing operation of parsing a
BB frame header to obtain IP header compression information; a header de compression operation of de-compressing headers of IP packets included in a BB frame by using the IP header compression information; and a packet recombining operation of
combining the IP packets to output an IP stream, wherein the IP header compression information includes IP packet type information and IP packet position information for the IP packets, wherein the IP packet position information indicates a position of
each of the IP packets within the BB frame and the IP packet type information indicates whether each of the IP packets includes a full header or a partial header.

13. The method of claim 12, wherein the IP packet position information is start position information of the IP packets within the signal frame or length information of the IP packets within the signal frame.

14. The method of claim 12, wherein the IP header compression information is included in an extension field of the BB frame header.

Description

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to an apparatus for transmitting broadcast signals, an apparatus for receiving broadcast signals and methods for transmitting and receiving broadcast signals.

Discussion of the Related Art

As analog broadcast signal transmission comes to an end, various technologies for transmitting/receiving digital broadcast signals are being developed. A digital broadcast signal may include a larger amount of video/audio data than an analog
broadcast signal and further include various types of additional data in addition to the video/audio data.

That is, a digital broadcast system can provide HD (high definition) images, multi-channel audio and various additional services. However, data transmission efficiency for transmission of large amounts of data, robustness of
transmission/reception networks and network flexibility in consideration of mobile reception equipment need to be improved for digital broadcast.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an apparatus and method for transmitting broadcast signals to multiplex data of a broadcast transmission/reception system providing two or more different broadcast services in a time domain and
transmit the multiplexed data through the same RF signal bandwidth and an apparatus and method for receiving broadcast signals corresponding thereto.

Another object of the present invention is to provide an apparatus for transmitting broadcast signals, an apparatus for receiving broadcast signals and methods for transmitting and receiving broadcast signals to classify data corresponding to
services by components, transmit data corresponding to each component as a data pipe, receive and process the data

Still another object of the present invention is to provide an apparatus for transmitting broadcast signals, an apparatus for receiving broadcast signals and methods for transmitting and receiving broadcast signals to signal signaling
information necessary to provide broadcast signals.

Accordingly, it is an object of the present invention is to provide an apparatus for transmitting a broadcast signal, the apparatus comprising: an input formatter module configured to de-multiplex an input stream into at least one data pipe
(DP); a BICM module configured to perform error correction on data of the at least one DP; a frame building module configured to generate a signal frame including the data of the DP; and an OFDM generation module configured to generate a transmission
signal by inserting a preamble into the signal frame and performing OFDM modulation, wherein the input formatting module comprises: a header compression module configured to compress IP headers of IP packets included in an IP stream when the input stream
is the IP stream; a baseband (BB) frame slicer module configured to allocate data of the IP packets to a BB frame; and a BB frame header insertion module configured to insert a BB frame header into the BB frame.

Another object of the present invention is to provide an apparatus for receiving a broadcast signal, the apparatus comprising: a synchronization/demodulation module configured to perform signal detection and OFDM demodulation on a received
broadcast signal; a frame parsing module configured to parse a signal frame of the broadcast signal to extract service data; a demapping/decoding module configured to convert an input signal into a bit domain and perform deinterleaving on the converted
bit domain; and an output processing module configured to receive the service data and output a data stream, wherein the output processing module comprises: a baseband (BB) frame header parser module configured to parse a BB frame header to obtain IP
header compression information; a header de-compression module configured to de-compress headers of IP packets included in the BB frame by using the IP header compression information; and a packet recombining module configured to combine the IP packets
to output an IP stream.

The present invention can process data according to service characteristics to control QoS (Quality of Services) for each service or service component, thereby providing various broadcast services.

The present invention can achieve transmission flexibility by transmitting various broadcast services through the same RF signal bandwidth.

The present invention can improve data transmission efficiency and increase robustness of transmission/reception of broadcast signals using a MIMO system.

According to the present invention, it is possible to provide broadcast signal transmission and reception methods and apparatus capable of receiving digital broadcast signals without error even with mobile reception equipment or in an indoor
environment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a structure of an apparatus for transmitting broadcast signals for future broadcast services according to an embodiment of the present invention.

FIG. 2 illustrates an input formatting block according to one embodiment of the present invention.

FIG. 3 illustrates an input formatting block according to another embodiment of the present invention.

FIG. 4 illustrates an input formatting block according to another embodiment of the present invention.

FIG. 5 illustrates a BICM block according to an embodiment of the present invention.

FIG. 6 illustrates a BICM block according to another embodiment of the present invention.

FIG. 7 illustrates a frame building block according to one embodiment of the present invention.

FIG. 8 illustrates an OFDM generation block according to an embodiment of the present invention.

FIG. 9 illustrates a structure of an apparatus for receiving broadcast signals for future broadcast services according to an embodiment of the present invention.

FIG. 10 illustrates a frame structure according to an embodiment of the present invention.

FIG. 11 illustrates a signaling hierarchy structure of the frame according to an embodiment of the present invention.

FIG. 12 illustrates preamble signaling data according to an embodiment of the present invention.

FIG. 13 illustrates PLS1 data according to an embodiment of the present invention.

FIG. 14 illustrates PLS2 data according to an embodiment of the present invention.

FIG. 15 illustrates PLS2 data according to another embodiment of the present invention.

FIG. 16 illustrates a logical structure of a frame according to an embodiment of the present invention.

FIG. 17 illustrates PLS mapping according to an embodiment of the present invention.

FIG. 18 illustrates EAC mapping according to an embodiment of the present invention.

FIG. 19 illustrates FIC mapping according to an embodiment of the present invention.

FIG. 20 illustrates a type of DP according to an embodiment of the present invention.

FIG. 21 illustrates DP mapping according to an embodiment of the present invention.

FIG. 22 illustrates an FEC structure according to an embodiment of the present invention.

FIG. 23 illustrates a bit interleaving according to an embodiment of the present invention.

FIG. 24 illustrates a cell-word demultiplexing according to an embodiment of the present invention.

FIG. 25 illustrates a time interleaving according to an embodiment of the present invention.

FIG. 26 is a view illustrating a mode adaptation module of a broadcast signal transmitter according to an embodiment of the present invention.

FIG. 27 is a view illustrating an output processor module of a broadcast signal receiver according to an embodiment of the present invention.

FIG. 28 is a view illustrating a method of compressing an IP header according to an embodiment of the present invention.

FIG. 29 is a view illustrating a method of compressing an IP header according to another embodiment of the present invention.

FIG. 30 is a view illustrating a method of signaling header compression information according to an embodiment of the present invention.

FIG. 31 is a view illustrating a method of signaling header compression information according to another embodiment of the present invention.

FIG. 32 is a view illustrating a method of signaling header compression information according to another embodiment of the present invention.

FIG. 33 is a view illustrating an embodiment of a scheme of expressing a packet length of FIG. 32.

FIG. 34 is a view illustrating a BB frame configuration of IP header compression methods according to an embodiment of the present invention.

FIG. 35 is a view illustrating a BB frame configuration of IP header compression methods and an error checking method according to an embodiment of the present invention.

FIG. 36 is a view illustrating a BB frame configuration of IP header compression methods and a packet accessing method according to an embodiment of the present invention.

FIG. 37 is a view illustrating a BB frame configuration and a packet accessing method according to an embodiment of the present invention.

FIG. 38 is a view illustrating a method for transmitting a broadcast signal according to an embodiment of the present invention.

FIG. 39 is a view illustrating a method for receiving a broadcast signal according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The detailed description, which will be given below with reference to the accompanying
drawings, is intended to explain exemplary embodiments of the present invention, rather than to show the only embodiments that can be implemented according to the present invention. The following detailed description includes specific details in order
to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without such specific details.

Although most terms used in the present invention have been selected from general ones widely used in the art, some terms have been arbitrarily selected by the applicant and their meanings are explained in detail in the following description as
needed. Thus, the present invention should be understood based upon the intended meanings of the terms rather than their simple names or meanings. Also, the term block and module are used similarly to indicate logical/functional unit of particular
signal/data processing.

The present invention provides apparatuses and methods for transmitting and receiving broadcast signals for future broadcast services. Future broadcast services according to an embodiment of the present invention include a terrestrial broadcast
service, a mobile broadcast service, a UHDTV service, etc. The present invention may process broadcast signals for the future broadcast services through non-MIMO (Multiple Input Multiple Output) or MIMO according to one embodiment. A non-MIMO scheme
according to an embodiment of the present invention may include a MISO (Multiple Input Single Output) scheme, a SISO (Single Input Single Output) scheme, etc.

While MISO or MIMO uses two antennas in the following for convenience of description, the present invention is applicable to systems using two or more antennas.

The present invention may defines three physical layer (PL) profiles--base, handheld and advanced profiles-each optimized to minimize receiver complexity while attaining the performance required for a particular use case. The physical layer
(PHY) profiles are subsets of all configurations that a corresponding receiver should implement.

The three PHY profiles share most of the functional blocks but differ slightly in specific blocks and/or parameters. Additional PHY profiles can be defined in the future. For the system evolution, future profiles can also be multiplexed with
the existing profiles in a single RF channel through a future extension frame (FEF). The details of each PHY profile are described below.

1. Base Profile

The base profile represents a main use case for fixed receiving devices that are usually connected to a roof-top antenna. The base profile also includes portable devices that could be transported to a place but belong to a relatively stationary
reception category. Use of the base profile could be extended to handheld devices or even vehicular by some improved implementations, but those use cases are not expected for the base profile receiver operation.

Target SNR range of reception is from approximately to 20 dB, which includes the 15 dB SNR reception capability of the existing broadcast system (e.g. ATSC A/53). The receiver complexity and power consumption is not as critical as in the
battery-operated handheld devices, which will use the handheld profile. Key system parameters for the base profile are listed in below table 1.

The handheld profile is designed for use in handheld and vehicular devices that operate with battery power. The devices can be moving with pedestrian or vehicle speed. The power consumption as well as the receiver complexity is very important
for the implementation of the devices of the handheld profile. The target SNR range of the handheld profile is approximately 0 to 10 dB, but can be configured to reach below 0 dB when intended for deeper indoor reception.

In addition to low SNR capability, resilience to the Doppler Effect caused by receiver mobility is the most important performance attribute of the handheld profile. Key system parameters for the handheld profile are listed in the below table 2.

The advanced profile provides highest channel capacity at the cost of more implementation complexity. This profile requires using MIMO transmission and reception, and UHDTV service is a target use case for which this profile is specifically
designed. The increased capacity can also be used to allow an increased number of services in a given bandwidth, e.g., multiple SDTV or HDTV services.

The target SNR range of the advanced profile is approximately 20 to 30 dB. MIMO transmission may initially use existing elliptically-polarized transmission equipment, with extension to full-power cross-polarized transmission in the future. Key
system parameters for the advanced profile are listed in below table 3.

In this case, the base profile can be used as a profile for both the terrestrial broadcast service and the mobile broadcast service. That is, the base profile can be used to define a concept of a profile which includes the mobile profile.
Also, the advanced profile can be divided advanced profile for a base profile with MIMO and advanced profile for a handheld profile with MIMO. Moreover, the three profiles can be changed according to intention of the designer.

The following terms and definitions may apply to the present invention. The following terms and definitions can be changed according to design.

auxiliary stream: sequence of cells carrying data of as yet undefined modulation and coding, which may be used for future extensions or as required by broadcasters or network operators

base data pipe: data pipe that carries service signaling data

baseband frame (or BBFRAME): set of Kbch bits which form the input to one FEC encoding process (BCH and LDPC encoding)

cell: modulation value that is carried by one carrier of the OFDM transmission

coded block: LDPC-encoded block of PLS1 data or one of the LDPC-encoded blocks of PLS2 data

data pipe: logical channel in the physical layer that carries service data or related metadata, which may carry one or multiple service(s) or service component(s).

data pipe unit: a basic unit for allocating data cells to a DP in a frame.

data symbol: OFDM symbol in a frame which is not a preamble symbol (the frame signaling symbol and frame edge symbol is included in the data symbol)

DP_ID: this 8-bit field identifies uniquely a DP within the system identified by the SYSTEM_ID

dummy cell: cell carrying a pseudo-random value used to fill the remaining capacity not used for PLS signaling, DPs or auxiliary streams

emergency alert channel: part of a frame that carries EAS information data

frame: physical layer time slot that starts with a preamble and ends with a frame edge symbol

frame repetition unit: a set of frames belonging to same or different physical layer profile including a FEF, which is repeated eight times in a super-frame

fast information channel: a logical channel in a frame that carries the mapping information between a service and the corresponding base DP

FECBLOCK: set of LDPC-encoded bits of a DP data

FFT size: nominal FFT size used for a particular mode, equal to the active symbol period Ts expressed in cycles of the elementary period T

frame signaling symbol: OFDM symbol with higher pilot density used at the start of a frame in certain combinations of FFT size, guard interval and scattered pilot (sp) pattern, which carries a part of the PLS data

frame edge symbol: OFDM symbol with higher pilot density used at the end of a frame in certain combinations of FFT size, guard interval and scattered pilot pattern

frame-group: the set of all the frames having the same PHY profile type in a super-frame.

future extension frame: physical layer time slot within the super-frame that could be used for future extension, which starts with a preamble

Futurecast UTB system: proposed physical layer broadcasting system, of which the input is one or more MPEG2-TS or IP or general stream(s) and of which the output is an RF signal

input stream: A stream of data for an ensemble of services delivered to the end users by the system.

PHY profile: subset of all configurations that a corresponding receiver should implement

PLS: physical layer signaling data consisting of PLS1 and PLS2

PLS1: a first set of PLS data carried in the FSS symbols having a fixed size, coding and modulation, which carries basic information about the system as well as the parameters needed to decode the PLS2

NOTE: PLS1 data remains constant for the duration of a frame-group.

PLS2: a second set of PLS data transmitted in the FSS symbol, which carries more detailed PLS data about the system and the DPs

PLS2 static data: PLS2 data that remains static for the duration of a frame-group

preamble signaling data: signaling data carried by the preamble symbol and used to identify the basic mode of the system

preamble symbol: fixed-length pilot symbol that carries basic PLS data and is located in the beginning of a frame

NOTE: The preamble symbol is mainly used for fast initial band scan to detect the system signal, its timing, frequency offset, and FFT-size.

reserved for future use: not defined by the present document but may be defined in future

super-frame: set of eight frame repetition units

time interleaving block (TI block): set of cells within which time interleaving is carried out, corresponding to one use of the time interleaver memory

TI group: unit over which dynamic capacity allocation for a particular DP is carried out, made up of an integer, dynamically varying number of XFECBLOCKs

NOTE: The TI group may be mapped directly to one frame or may be mapped to multiple frames. It may contain one or more TI blocks.

Type 1 DP: DP of a frame where all DPs are mapped into the frame in TDM fashion

Type 2 DP: DP of a frame where all DPs are mapped into the frame in FDM fashion

XFECBLOCK: set of Ncells cells carrying all the bits of one LDPC FECBLOCK

FIG. 1 illustrates a structure of an apparatus for transmitting broadcast signals for future broadcast services according to an embodiment of the present invention.

The apparatus for transmitting broadcast signals for future broadcast services according to an embodiment of the present invention can include an input formatting block 1000, a BICM (Bit interleaved coding & modulation) block 1010, a frame
structure block 1020, an OFDM (Orthogonal Frequency Division Multiplexing) generation block 1030 and a signaling generation block 1040. A description will be given of the operation of each module of the apparatus for transmitting broadcast signals.

IP stream/packets and MPEG2-TS are the main input formats, other stream types are handled as General Streams. In addition to these data inputs, Management Information is input to control the scheduling and allocation of the corresponding
bandwidth for each input stream. One or multiple TS stream(s), IP stream(s) and/or General Stream(s) inputs are simultaneously allowed.

The input formatting block 1000 can demultiplex each input stream into one or multiple data pipe(s), to each of which an independent coding and modulation is applied. The data pipe (DP) is the basic unit for robustness control, thereby
affecting quality-of-service (QoS). One or multiple service(s) or service component(s) can be carried by a single DP. Details of operations of the input formatting block 1000 will be described later.

The data pipe is a logical channel in the physical layer that carries service data or related metadata, which may carry one or multiple service(s) or service component(s).

Also, the data pipe unit: a basic unit for allocating data cells to a DP in a frame.

In the BICM block 1010, parity data is added for error correction and the encoded bit streams are mapped to complex-value constellation symbols. The symbols are interleaved across a specific interleaving depth that is used for the corresponding
DP. For the advanced profile, MIMO encoding is performed in the BICM block 1010 and the additional data path is added at the output for MIMO transmission. Details of operations of the BICM block 1010 will be described later.

The Frame Building block 1020 can map the data cells of the input DPs into the OFDM symbols within a frame. After mapping, the frequency interleaving is used for frequency-domain diversity, especially to combat frequency-selective fading
channels. Details of operations of the Frame Building block 1020 will be described later.

After inserting a preamble at the beginning of each frame, the OFDM Generation block 1030 can apply conventional OFDM modulation having a cyclic prefix as guard interval. For antenna space diversity, a distributed MISO scheme is applied across
the transmitters. In addition, a Peak-to-Average Power Reduction (PAPR) scheme is performed in the time domain. For flexible network planning, this proposal provides a set of various FFT sizes, guard interval lengths and corresponding pilot patterns.
Details of operations of the OFDM Generation block 1030 will be described later.

The Signaling Generation block 1040 can create physical layer signaling information used for the operation of each functional block. This signaling information is also transmitted so that the services of interest are properly recovered at the
receiver side. Details of operations of the Signaling Generation block 1040 will be described later.

FIGS. 2, 3 and 4 illustrate the input formatting block 1000 according to embodiments of the present invention. A description will be given of each figure.

FIG. 2 illustrates an input formatting block according to one embodiment of the present invention. FIG. 2 shows an input formatting module when the input signal is a single input stream.

The input formatting block illustrated in FIG. 2 corresponds to an embodiment of the input formatting block 1000 described with reference to FIG. 1.

The input to the physical layer may be composed of one or multiple data streams. Each data stream is carried by one DP. The mode adaptation modules slice the incoming data stream into data fields of the baseband frame (BBF). The system
supports three types of input data streams: MPEG2-TS, Internet protocol (IP) and Generic stream (GS). MPEG2-TS is characterized by fixed length (188 byte) packets with the first byte being a sync-byte (0x47). An IP stream is composed of variable length
IP datagram packets, as signaled within IP packet headers. The system supports both IPv4 and IPv6 for the IP stream. GS may be composed of variable length packets or constant length packets, signaled within encapsulation packet headers.

(a) shows a mode adaptation block 2000 and a stream adaptation 2010 for signal DP and (b) shows a PLS generation block 2020 and a PLS scrambler 2030 for generating and processing PLS data. A description will be given of the operation of each
block.

The CRC Encoder provides three kinds of CRC encoding for error detection at the user packet (UP) level, i.e., CRC-8, CRC-16, and CRC-32. The computed CRC bytes are appended after the UP. CRC-8 is used for TS stream and CRC-32 for IP stream.
If the GS stream doesn't provide the CRC encoding, the proposed CRC encoding should be applied.

BB Frame Slicer maps the input into an internal logical-bit format. The first received bit is defined to be the MSB. The BB Frame Slicer allocates a number of input bits equal to the available data field capacity. To allocate a number of
input bits equal to the BBF payload, the UP packet stream is sliced to fit the data field of BBF.

BB Frame Header Insertion block can insert fixed length BBF header of 2 bytes is inserted in front of the BB Frame. The BBF header is composed of STUFFI (1 bit), SYNCD (13 bits), and RFU (2 bits). In addition to the fixed 2-Byte BBF header,
BBF can have an extension field (1 or 3 bytes) at the end of the 2-byte BBF header.

The stream adaptation 2010 is comprised of stuffing insertion block and BB scrambler.

The stuffing insertion block can insert stuffing field into a payload of a BB frame. If the input data to the stream adaptation is sufficient to fill a BB-Frame, STUFFI is set to `0` and the BBF has no stuffing field. Otherwise STUFFI is set
to `1` and the stuffing field is inserted immediately after the BBF header. The stuffing field comprises two bytes of the stuffing field header and a variable size of stuffing data.

The BB scrambler scrambles complete BBF for energy dispersal. The scrambling sequence is synchronous with the BBF. The scrambling sequence is generated by the feed-back shift register.

The PLS1 data is a first set of PLS data carried in the FSS symbols in the frame having a fixed size, coding and modulation, which carries basic information about the system as well as the parameters needed to decode the PLS2 data. The PLS1
data provides basic transmission parameters including parameters required to enable the reception and decoding of the PLS2 data. Also, the PLS1 data remains constant for the duration of a frame-group.

The PLS2 data is a second set of PLS data transmitted in the FSS symbol, which carries more detailed PLS data about the system and the DPs. The PLS2 contains parameters that provide sufficient information for the receiver to decode the desired
DP. The PLS2 signaling further consists of two types of parameters, PLS2 Static data (PLS2-STAT data) and PLS2 dynamic data (PLS2-DYN data). The PLS2 Static data is PLS2 data that remains static for the duration of a frame-group and the PLS2 dynamic
data is PLS2 data that may dynamically change frame-by-frame.

Details of the PLS data will be described later.

The PLS scrambler 2030 can scramble the generated PLS data for energy dispersal.

The above-described blocks may be omitted or replaced by blocks having similar or identical functions.

FIG. 3 illustrates an input formatting block according to another embodiment of the present invention.

The input formatting block illustrated in FIG. 3 corresponds to an embodiment of the input formatting block 1000 described with reference to FIG. 1.

The mode adaptation block of the input formatting block for processing the multiple input streams can independently process the multiple input streams.

Referring to FIG. 3, the mode adaptation block for respectively processing the multiple input streams can include an input stream splitter 3000, an input stream synchronizer 3010, a compensating delay block 3020, a null packet deletion block
3030, a head compression block 3040, a CRC encoder 3050, a BB frame slicer 3060 and a BB header insertion block 3070. Description will be given of each block of the mode adaptation block.

Operations of the CRC encoder 3050, BB frame slicer 3060 and BB header insertion block 3070 correspond to those of the CRC encoder, BB frame slicer and BB header insertion block described with reference to FIG. 2 and thus description thereof is
omitted.

The input stream splitter 3000 can split the input TS, IP, GS streams into multiple service or service component (audio, video, etc.) streams.

The input stream synchronizer 3010 may be referred as ISSY. The ISSY can provide suitable means to guarantee Constant Bit Rate (CBR) and constant end-to-end transmission delay for any input data format. The ISSY is always used for the case of
multiple DPs carrying TS, and optionally used for multiple DPs carrying GS streams.

The compensating delay block 3020 can delay the split TS packet stream following the insertion of ISSY information to allow a TS packet recombining mechanism without requiring additional memory in the receiver.

The null packet deletion block 3030, is used only for the TS input stream case. Some TS input streams or split TS streams may have a large number of null-packets present in order to accommodate VBR (variable bit-rate) services in a CBR TS
stream. In this case, in order to avoid unnecessary transmission overhead, null-packets can be identified and not transmitted. In the receiver, removed null-packets can be re-inserted in the exact place where they were originally by reference to a
deleted null-packet (DNP) counter that is inserted in the transmission, thus guaranteeing constant bit-rate and avoiding the need for time-stamp (PCR) updating.

The head compression block 3040 can provide packet header compression to increase transmission efficiency for TS or IP input streams. Because the receiver can have a priori information on certain parts of the header, this known information can
be deleted in the transmitter.

For Transport Stream, the receiver has a-priori information about the sync-byte configuration (0x47) and the packet length (188 Byte). If the input TS stream carries content that has only one PID, i.e., for only one service component (video,
audio, etc.) or service sub-component (SVC base layer, SVC enhancement layer, MVC base view or MVC dependent views), TS packet header compression can be applied (optionally) to the Transport Stream. IP packet header compression is used optionally if the
input steam is an IP stream.

The above-described blocks may be omitted or replaced by blocks having similar or identical functions.

FIG. 4 illustrates an input formatting block according to another embodiment of the present invention.

The input formatting block illustrated in FIG. 4 corresponds to an embodiment of the input formatting block 1000 described with reference to FIG. 1.

Referring to FIG. 4, the mode adaptation block for respectively processing the multiple input streams can include a scheduler 4000, an 1-Frame delay block 4010, a stuffing insertion block 4020, an in-band signaling 4030, a BB Frame scrambler
4040, a PLS generation block 4050 and a PLS scrambler 4060. Description will be given of each block of the stream adaptation block.

Operations of the stuffing insertion block 4020, the BB Frame scrambler 4040, the PLS generation block 4050 and the PLS scrambler 4060 correspond to those of the stuffing insertion block, BB scrambler, PLS generation block and the PLS scrambler
described with reference to FIG. 2 and thus description thereof is omitted.

The scheduler 4000 can determine the overall cell allocation across the entire frame from the amount of FECBLOCKs of each DP. Including the allocation for PLS, EAC and FIC, the scheduler generate the values of PLS2-DYN data, which is
transmitted as in-band signaling or PLS cell in FSS of the frame. Details of FECBLOCK, EAC and FIC will be described later.

The 1-Frame delay block 4010 can delay the input data by one transmission frame such that scheduling information about the next frame can be transmitted through the current frame for in-band signaling information to be inserted into the DPs.

The in-band signaling 4030 can insert un-delayed part of the PLS2 data into a DP of a frame.

The above-described blocks may be omitted or replaced by blocks having similar or identical functions.

FIG. 5 illustrates a BICM block according to an embodiment of the present invention.

The BICM block illustrated in FIG. 5 corresponds to an embodiment of the BICM block 1010 described with reference to FIG. 1.

As described above, the apparatus for transmitting broadcast signals for future broadcast services according to an embodiment of the present invention can provide a terrestrial broadcast service, mobile broadcast service, UHDTV service, etc.

Since QoS (quality of service) depends on characteristics of a service provided by the apparatus for transmitting broadcast signals for future broadcast services according to an embodiment of the present invention, data corresponding to
respective services needs to be processed through different schemes. Accordingly, the a BICM block according to an embodiment of the present invention can independently process DPs input thereto by independently applying SISO, MISO and MIMO schemes to
the data pipes respectively corresponding to data paths. Consequently, the apparatus for transmitting broadcast signals for future broadcast services according to an embodiment of the present invention can control QoS for each service or service
component transmitted through each DP.

(a) shows the BICM block shared by the base profile and the handheld profile and (b) shows the BICM block of the advanced profile.

The BICM block shared by the base profile and the handheld profile and the BICM block of the advanced profile can include plural processing blocks for processing each DP.

A description will be given of each processing block of the BICM block for the base profile and the handheld profile and the BICM block for the advanced profile.

A processing block 5000 of the BICM block for the base profile and the handheld profile can include a Data FEC encoder 5010, a bit interleaver 5020, a constellation mapper 5030, an SSD (Signal Space Diversity) encoding block 5040 and a time
interleaver 5050.

The Data FEC encoder 5010 can perform the FEC encoding on the input BBF to generate FECBLOCK procedure using outer coding (BCH), and inner coding (LDPC). The outer coding (BCH) is optional coding method. Details of operations of the Data FEC
encoder 5010 will be described later.

The bit interleaver 5020 can interleave outputs of the Data FEC encoder 5010 to achieve optimized performance with combination of the LDPC codes and modulation scheme while providing an efficiently implementable structure. Details of operations
of the bit interleaver 5020 will be described later.

The constellation mapper 5030 can modulate each cell word from the bit interleaver 5020 in the base and the handheld profiles, or cell word from the Cell-word demultiplexer 5010-1 in the advanced profile using either QPSK, QAM-16, non-uniform
QAM (NUQ-64, NUQ-256, NUQ-1024) or non-uniform constellation (NUC-16, NUC-64, NUC-256, NUC-1024) to give a power-normalized constellation point, el. This constellation mapping is applied only for DPs. Observe that QAM-16 and NUQs are square shaped,
while NUCs have arbitrary shape. When each constellation is rotated by any multiple of 90 degrees, the rotated constellation exactly overlaps with its original one. This "rotation-sense" symmetric property makes the capacities and the average powers of
the real and imaginary components equal to each other. Both NUQs and NUCs are defined specifically for each code rate and the particular one used is signaled by the parameter DP_MOD filed in PLS2 data.

The SSD encoding block 5040 can precode cells in two (2D), three (3D), and four (4D) dimensions to increase the reception robustness under difficult fading conditions.

The time interleaver 5050 can operates at the DP level. The parameters of time interleaving (TI) may be set differently for each DP. Details of operations of the time interleaver 5050 will be described later.

A processing block 5000-1 of the BICM block for the advanced profile can include the Data FEC encoder, bit interleaver, constellation mapper, and time interleaver. However, the processing block 5000-1 is distinguished from the processing block
5000 further includes a cell-word demultiplexer 5010-1 and a MIMO encoding block 5020-1.

Also, the operations of the Data FEC encoder, bit interleaver, constellation mapper, and time interleaver in the processing block 5000-1 correspond to those of the Data FEC encoder 5010, bit interleaver 5020, constellation mapper 5030, and time
interleaver 5050 described and thus description thereof is omitted.

The cell-word demultiplexer 5010-1 is used for the DP of the advanced profile to divide the single cell-word stream into dual cell-word streams for MIMO processing. Details of operations of the cell-word demultiplexer 5010-1 will be described
later.

The MIMO encoding block 5020-1 can processing the output of the cell-word demultiplexer 5010-1 using MIMO encoding scheme. The MIMO encoding scheme was optimized for broadcasting signal transmission. The MIMO technology is a promising way to
get a capacity increase but it depends on channel characteristics. Especially for broadcasting, the strong LOS component of the channel or a difference in the received signal power between two antennas caused by different signal propagation
characteristics makes it difficult to get capacity gain from MIMO. The proposed MIMO encoding scheme overcomes this problem using a rotation-based pre-coding and phase randomization of one of the MIMO output signals.

MIMO encoding is intended for a 2.times.2 MIMO system requiring at least two antennas at both the transmitter and the receiver. Two MIMO encoding modes are defined in this proposal; full-rate spatial multiplexing (FR-SM) and full-rate
full-diversity spatial multiplexing (FRFD-SM). The FR-SM encoding provides capacity increase with relatively small complexity increase at the receiver side while the FRFD-SM encoding provides capacity increase and additional diversity gain with a great
complexity increase at the receiver side. The proposed MIMO encoding scheme has no restriction on the antenna polarity configuration.

MIMO processing is required for the advanced profile frame, which means all DPs in the advanced profile frame are processed by the MIMO encoder. MIMO processing is applied at DP level. Pairs of the Constellation Mapper outputs NUQ (e1,i and
e2,i) are fed to the input of the MIMO Encoder. Paired MIMO Encoder output (g1,i and g2,i) is transmitted by the same carrier k and OFDM symbol 1 of their respective TX antennas.

The above-described blocks may be omitted or replaced by blocks having similar or identical functions.

FIG. 6 illustrates a BICM block according to another embodiment of the present invention.

The BICM block illustrated in FIG. 6 corresponds to an embodiment of the BICM block 1010 described with reference to FIG. 1.

FIG. 6 illustrates a BICM block for protection of physical layer signaling (PLS), emergency alert channel (EAC) and fast information channel (FIC). EAC is a part of a frame that carries EAS information data and FIC is a logical channel in a
frame that carries the mapping information between a service and the corresponding base DP. Details of the EAC and FIC will be described later.

Referring to FIG. 6, the BICM block for protection of PLS, EAC and FIC can include a PLS FEC encoder 6000, a bit interleaver 6010, a constellation mapper 6020 and time interleaver 6030.

Also, the PLS FEC encoder 6000 can include a scrambler, BCH encoding/zero insertion block, LDPC encoding block and LDPC parity punturing block. Description will be given of each block of the BICM block.

The scrambler can scramble PLS1 data and PLS2 data before BCH encoding and shortened and punctured LDPC encoding.

The BCH encoding/zero insertion block can perform outer encoding on the scrambled PLS 1/2 data using the shortened BCH code for PLS protection and insert zero bits after the BCH encoding. For PLS1 data only, the output bits of the zero
insertion may be permutted before LDPC encoding.

The LDPC parity punturing block can perform puncturing on the PLS1 data and PLS 2 data.

When shortening is applied to the PLS1 data protection, some LDPC parity bits are punctured after LDPC encoding. Also, for the PLS2 data protection, the LDPC parity bits of PLS2 are punctured after LDPC encoding. These punctured bits are not
transmitted.

The bit interleaver 6010 can interleave the each shortened and punctured PLS1 data and PLS2 data.

The time interleaver 6030 can interleave the mapped PLS1 data and PLS2 data.

The above-described blocks may be omitted or replaced by blocks having similar or identical functions.

FIG. 7 illustrates a frame building block according to one embodiment of the present invention.

The frame building block illustrated in FIG. 7 corresponds to an embodiment of the frame building block 1020 described with reference to FIG. 1.

Referring to FIG. 7, the frame building block can include a delay compensation block 7000, a cell mapper 7010 and a frequency interleaver 7020. Description will be given of each block of the frame building block.

The delay compensation block 7000 can adjust the timing between the data pipes and the corresponding PLS data to ensure that they are co-timed at the transmitter end. The PLS data is delayed by the same amount as data pipes are by addressing
the delays of data pipes caused by the Input Formatting block and BICM block. The delay of the BICM block is mainly due to the time interleaver 5050. In-band signaling data carries information of the next TI group so that they are carried one frame
ahead of the DPs to be signaled. The Delay Compensating block delays in-band signaling data accordingly.

The cell mapper 7010 can map PLS, EAC, FIC, DPs, auxiliary streams and dummy cells into the active carriers of the OFDM symbols in the frame. The basic function of the cell mapper 7010 is to map data cells produced by the TIs for each of the
DPs, PLS cells, and EAC/FIC cells, if any, into arrays of active OFDM cells corresponding to each of the OFDM symbols within a frame. Service signaling data (such as PSI (program specific information)/SI) can be separately gathered and sent by a data
pipe. The Cell Mapper operates according to the dynamic information produced by the scheduler and the configuration of the frame structure. Details of the frame will be described later.

The frequency interleaver 7020 can randomly interleave data cells received from the cell mapper 7010 to provide frequency diversity. Also, the frequency interleaver 7020 can operate on very OFDM symbol pair comprised of two sequential OFDM
symbols using a different interleaving-seed order to get maximum interleaving gain in a single frame. Details of operations of the frequency interleaver 7020 will be described later.

The above-described blocks may be omitted or replaced by blocks having similar or identical functions.

FIG. 8 illustrates an OFMD generation block according to an embodiment of the present invention.

The OFMD generation block illustrated in FIG. 8 corresponds to an embodiment of the OFMD generation block 1030 described with reference to FIG. 1.

The OFDM generation block modulates the OFDM carriers by the cells produced by the Frame Building block, inserts the pilots, and produces the time domain signal for transmission. Also, this block subsequently inserts guard intervals, and
applies PAPR (Peak-to-Average Power Radio) reduction processing to produce the final RF signal.

Referring to FIG. 8, the frame building block can include a pilot and reserved tone insertion block 8000, a 2D-eSFN encoding block 8010, an IFFT (Inverse Fast Fourier Transform) block 8020, a PAPR reduction block 8030, a guard interval insertion
block 8040, a preamble insertion block 8050, other system insertion block 8060 and a DAC block 8070. Description will be given of each block of the frame building block.

The pilot and reserved tone insertion block 8000 can insert pilots and the reserved tone.

Various cells within the OFDM symbol are modulated with reference information, known as pilots, which have transmitted values known a priori in the receiver. The information of pilot cells is made up of scattered pilots (SP), continual pilots
(CP), edge pilots (EP), FSS (frame signaling symbol) pilots and FES (frame edge symbol) pilots. Each pilot is transmitted at a particular boosted power level according to pilot type and pilot pattern. The value of the pilot information is derived from
a reference sequence, which is a series of values, one for each transmitted carrier on any given symbol. The pilots can be used for frame synchronization, frequency synchronization, time synchronization, channel estimation, and transmission mode
identification, and also can be used to follow the phase noise.

Reference information, taken from the reference sequence, is transmitted in scattered pilot cells in every symbol except the preamble, FSS and FES of the frame. Continual pilots are inserted in every symbol of the frame. The number and
location of continual pilots depends on both the FFT size and the scattered pilot pattern. The edge carriers are edge pilots in every symbol except for the preamble symbol. They are inserted in order to allow frequency interpolation up to the edge of
the spectrum. FSS pilots are inserted in FSS(s) and FES pilots are inserted in FES. They are inserted in order to allow time interpolation up to the edge of the frame.

The system according to an embodiment of the present invention supports the SFN network, where distributed MISO scheme is optionally used to support very robust transmission mode. The 2D-eSFN is a distributed MISO scheme that uses multiple TX
antennas, each of which is located in the different transmitter site in the SFN network.

The 2D-eSFN encoding block 8010 can process a 2D-eSFN processing to distorts the phase of the signals transmitted from multiple transmitters, in order to create both time and frequency diversity in the SFN configuration. Hence, burst errors due
to low flat fading or deep-fading for a long time can be mitigated.

The IFFT block 8020 can modulate the output from the 2D-eSFN encoding block 8010 using OFDM modulation scheme. Any cell in the data symbols which has not been designated as a pilot (or as a reserved tone) carries one of the data cells from the
frequency interleaver. The cells are mapped to OFDM carriers.

The PAPR reduction block 8030 can perform a PAPR reduction on input signal using various PAPR reduction algorithm in the time domain.

The guard interval insertion block 8040 can insert guard intervals and the preamble insertion block 8050 can insert preamble in front of the signal. Details of a structure of the preamble will be described later. The other system insertion
block 8060 can multiplex signals of a plurality of broadcast transmission/reception systems in the time domain such that data of two or more different broadcast transmission/reception systems providing broadcast services can be simultaneously transmitted
in the same RF signal bandwidth. In this case, the two or more different broadcast transmission/reception systems refer to systems providing different broadcast services. The different broadcast services may refer to a terrestrial broadcast service,
mobile broadcast service, etc. Data related to respective broadcast services can be transmitted through different frames.

The DAC block 8070 can convert an input digital signal into an analog signal and output the analog signal. The signal output from the DAC block 7800 can be transmitted through multiple output antennas according to the physical layer profiles.
A Tx antenna according to an embodiment of the present invention can have vertical or horizontal polarity.

The above-described blocks may be omitted or replaced by blocks having similar or identical functions according to design.

FIG. 9 illustrates a structure of an apparatus for receiving broadcast signals for future broadcast services according to an embodiment of the present invention.

The apparatus for receiving broadcast signals for future broadcast services according to an embodiment of the present invention can correspond to the apparatus for transmitting broadcast signals for future broadcast services, described with
reference to FIG. 1.

The apparatus for receiving broadcast signals for future broadcast services according to an embodiment of the present invention can include a synchronization & demodulation module 9000, a frame parsing module 9010, a demapping & decoding module
9020, an output processor 9030 and a signaling decoding module 9040. A description will be given of operation of each module of the apparatus for receiving broadcast signals.

The synchronization & demodulation module 9000 can receive input signals through m Rx antennas, perform signal detection and synchronization with respect to a system corresponding to the apparatus for receiving broadcast signals and carry out
demodulation corresponding to a reverse procedure of the procedure performed by the apparatus for transmitting broadcast signals.

The frame parsing module 9010 can parse input signal frames and extract data through which a service selected by a user is transmitted. If the apparatus for transmitting broadcast signals performs interleaving, the frame parsing module 9010 can
carry out deinterleaving corresponding to a reverse procedure of interleaving. In this case, the positions of a signal and data that need to be extracted can be obtained by decoding data output from the signaling decoding module 9400 to restore
scheduling information generated by the apparatus for transmitting broadcast signals.

The demapping & decoding module 9020 can convert the input signals into bit domain data and then deinterleave the same as necessary. The demapping & decoding module 9200 can perform demapping for mapping applied for transmission efficiency and
correct an error generated on a transmission channel through decoding. In this case, the demapping & decoding module 9020 can obtain transmission parameters necessary for demapping and decoding by decoding the data output from the signaling decoding
module 9040.

The output processor 9030 can perform reverse procedures of various compression/signal processing procedures which are applied by the apparatus for transmitting broadcast signals to improve transmission efficiency. In this case, the output
processor 9030 can acquire necessary control information from data output from the signaling decoding module 9040. The output of the output processor 9030 corresponds to a signal input to the apparatus for transmitting broadcast signals and may be
MPEG-TSs, IP streams (v4 or v6) and generic streams.

FIG. 10 illustrates a frame structure according to an embodiment of the present invention.

FIG. 10 shows an example configuration of the frame types and FRUs in a super-frame. (a) shows a super frame according to an embodiment of the present invention, (b) shows FRU (Frame Repetition Unit) according to an embodiment of the present
invention, (c) shows frames of variable PHY profiles in the FRU and (d) shows a structure of a frame.

A super-frame may be composed of eight FRUs. The FRU is a basic multiplexing unit for TDM of the frames, and is repeated eight times in a super-frame.

Each frame in the FRU belongs to one of the PHY profiles, (base, handheld, advanced) or FEF. The maximum allowed number of the frames in the FRU is four and a given PHY profile can appear any number of times from zero times to four times in the
FRU (e.g., base, base, handheld, advanced). PHY profile definitions can be extended using reserved values of the PHY_PROFILE in the preamble, if required.

The FEF part is inserted at the end of the FRU, if included. When the FEF is included in the FRU, the minimum number of FEFs is 8 in a super-frame. It is not recommended that FEF parts be adjacent to each other.

One frame is further divided into a number of OFDM symbols and a preamble. As shown in (d), the frame comprises a preamble, one or more frame signaling symbols (FSS), normal data symbols and a frame edge symbol (FES).

The preamble is a special symbol that enables fast Futurecast UTB system signal detection and provides a set of basic transmission parameters for efficient transmission and reception of the signal. The detailed description of the preamble will
be will be described later.

The main purpose of the FSS(s) is to carry the PLS data. For fast synchronization and channel estimation, and hence fast decoding of PLS data, the FSS has more dense pilot pattern than the normal data symbol. The FES has exactly the same
pilots as the FSS, which enables frequency-only interpolation within the FES and temporal interpolation, without extrapolation, for symbols immediately preceding the FES.

FIG. 11 illustrates a signaling hierarchy structure of the frame according to an embodiment of the present invention.

FIG. 11 illustrates the signaling hierarchy structure, which is split into three main parts: the preamble signaling data 11000, the PLS1 data 11010 and the PLS2 data 11020. The purpose of the preamble, which is carried by the preamble symbol in
every frame, is to indicate the transmission type and basic transmission parameters of that frame. The PLS1 enables the receiver to access and decode the PLS2 data, which contains the parameters to access the DP of interest. The PLS2 is carried in
every frame and split into two main parts: PLS2-STAT data and PLS2-DYN data. The static and dynamic portion of PLS2 data is followed by padding, if necessary.

FIG. 12 illustrates preamble signaling data according to an embodiment of the present invention.

Preamble signaling data carries 21 bits of information that are needed to enable the receiver to access PLS data and trace DPs within the frame structure. Details of the preamble signaling data are as follows:

PHY_PROFILE: This 3-bit field indicates the PHY profile type of the current frame. The mapping of different PHY profile types is given in below table 5.

EAC_FLAG: This 1 bit field indicates whether the EAC is provided in the current frame. If this field is set to `1`, emergency alert service (EAS) is provided in the current frame. If this field set to `0`, EAS is not carried in the current
frame. This field can be switched dynamically within a super-frame.

PILOT_MODE: This 1-bit field indicates whether the pilot mode is mobile mode or fixed mode for the current frame in the current frame-group. If this field is set to `0`, mobile pilot mode is used. If the field is set to `1`, the fixed pilot
mode is used.

PAPR_FLAG: This 1-bit field indicates whether PAPR reduction is used for the current frame in the current frame-group. If this field is set to value `1`, tone reservation is used for PAPR reduction. If this field is set to `0`, PAPR reduction
is not used.

FRU_CONFIGURE: This 3-bit field indicates the PHY profile type configurations of the frame repetition units (FRU) that are present in the current super-frame. All profile types conveyed in the current super-frame are identified in this field in
all preambles in the current super-frame. The 3-bit field has a different definition for each profile, as show in below table 8.

FIG. 13 illustrates PLS1 data according to an embodiment of the present invention.

PLS1 data provides basic transmission parameters including parameters required to enable the reception and decoding of the PLS2. As above mentioned, the PLS1 data remain unchanged for the entire duration of one frame-group. The detailed
definition of the signaling fields of the PLS1 data are as follows:

PREAMBLE_DATA: This 20-bit field is a copy of the preamble signaling data excluding the EAC_FLAG.

NUM_FRAME_FRU: This 2-bit field indicates the number of the frames per FRU.

PAYLOAD_TYPE: This 3-bit field indicates the format of the payload data carried in the frame-group. PAYLOAD_TYPE is signaled as shown in table 9.

NUM_FSS: This 2-bit field indicates the number of FSS symbols in the current frame.

SYSTEM_VERSION: This 8-bit field indicates the version of the transmitted signal format. The SYSTEM_VERSION is divided into two 4-bit fields, which are a major version and a minor version.

Major version: The MSB four bits of SYSTEM_VERSION field indicate major version information. A change in the major version field indicates a non-backward-compatible change. The default value is `0000`. For the version described in this
standard, the value is set to `0000`.

Minor version: The LSB four bits of SYSTEM_VERSION field indicate minor version information. A change in the minor version field is backward-compatible.

CELL_ID: This is a 16-bit field which uniquely identifies a geographic cell in an ATSC network. An ATSC cell coverage area may consist of one or more frequencies, depending on the number of frequencies used per Futurecast UTB system. If the
value of the CELL_ID is not known or unspecified, this field is set to `0`.

NETWORK_ID: This is a 16-bit field which uniquely identifies the current ATSC network.

SYSTEM_ID: This 16-bit field uniquely identifies the Futurecast UTB system within the ATSC network. The Futurecast UTB system is the terrestrial broadcast system whose input is one or more input streams (TS, IP, GS) and whose output is an RF
signal. The Futurecast UTB system carries one or more PHY profiles and FEF, if any. The same Futurecast UTB system may carry different input streams and use different RF frequencies in different geographical areas, allowing local service insertion.
The frame structure and scheduling is controlled in one place and is identical for all transmissions within a Futurecast UTB system. One or more Futurecast UTB systems may have the same SYSTEM_ID meaning that they all have the same physical layer
structure and configuration.

The following loop consists of FRU_PHY_PROFILE, FRU_FRAME_LENGTH, FRU_GI_FRACTION, and RESERVED which are used to indicate the FRU configuration and the length of each frame type. The loop size is fixed so that four PHY profiles (including a
FEF) are signaled within the FRU. If NUM_FRAME_FRU is less than 4, the unused fields are filled with zeros.

FRU_PHY_PROFILE: This 3-bit field indicates the PHY profile type of the (i+1)th (i is the loop index) frame of the associated FRU. This field uses the same signaling format as shown in the table 8.

FRU_FRAME_LENGTH: This 2-bit field indicates the length of the (i+1)th frame of the associated FRU. Using FRU_FRAME_LENGTH together with FRU_GI_FRACTION, the exact value of the frame duration can be obtained.

FRU_GI_FRACTION: This 3-bit field indicates the guard interval fraction value of the (i+1)th frame of the associated FRU. FRU_GI_FRACTION is signaled according to the table 7.

RESERVED: This 4-bit field is reserved for future use.

The following fields provide parameters for decoding the PLS2 data.

PLS2_FEC_TYPE: This 2-bit field indicates the FEC type used by the PLS2 protection. The FEC type is signaled according to table 10. The details of the LDPC codes will be described later.

PLS2_SIZE_CELL: This 15-bit field indicates Ctotal_partial_block, the size (specified as the number of QAM cells) of the collection of full coded blocks for PLS2 that is carried in the current frame-group. This value is constant during the
entire duration of the current frame-group.

PLS2_STAT_SIZE_BIT: This 14-bit field indicates the size, in bits, of the PLS2-STAT for the current frame-group. This value is constant during the entire duration of the current frame-group.

PLS2_DYN_SIZE_BIT: This 14-bit field indicates the size, in bits, of the PLS2-DYN for the current frame-group. This value is constant during the entire duration of the current frame-group.

PLS2_REP_FLAG: This 1-bit flag indicates whether the PLS2 repetition mode is used in the current frame-group. When this field is set to value `1`, the PLS2 repetition mode is activated. When this field is set to value `0`, the PLS2 repetition
mode is deactivated.

PLS2_REP_SIZE_CELL: This 15-bit field indicates Ctotal_partial_block, the size (specified as the number of QAM cells) of the collection of partial coded blocks for PLS2 carried in every frame of the current frame-group, when PLS2 repetition is
used. If repetition is not used, the value of this field is equal to 0. This value is constant during the entire duration of the current frame-group.

PLS2_NEXT_FEC_TYPE: This 2-bit field indicates the FEC type used for PLS2 that is carried in every frame of the next frame-group. The FEC type is signaled according to the table 10.

PLS2_NEXT_MOD: This 3-bit field indicates the modulation type used for PLS2 that is carried in every frame of the next frame-group. The modulation type is signaled according to the table 11.

PLS2_NEXT_REP_FLAG: This 1-bit flag indicates whether the PLS2 repetition mode is used in the next frame-group. When this field is set to value `1`, the PLS2 repetition mode is activated. When this field is set to value `0`, the PLS2
repetition mode is deactivated.

PLS 2_NEXT_REP_SIZE_CELL: This 15-bit field indicates Ctotal full block, The size (specified as the number of QAM cells) of the collection of full coded blocks for PLS2 that is carried in every frame of the next frame-group, when

PLS2 repetition is used. If repetition is not used in the next frame-group, the value of this field is equal to 0. This value is constant during the entire duration of the current frame-group.

PLS2_NEXT_REP_STAT_SIZE_BIT: This 14-bit field indicates the size, in bits, of the PLS2-STAT for the next frame-group. This value is constant in the current frame-group.

PLS2_NEXT_REP_DYN_SIZE_BIT: This 14-bit field indicates the size, in bits, of the PLS2-DYN for the next frame-group. This value is constant in the current frame-group.

PLS2_AP_MODE: This 2-bit field indicates whether additional parity is provided for PLS2 in the current frame-group. This value is constant during the entire duration of the current frame-group. The below table 12 gives the values of this
field. When this field is set to `00`, additional parity is not used for the PLS2 in the current frame-group.

PLS2_AP_SIZE_CELL: This 15-bit field indicates the size (specified as the number of QAM cells) of the additional parity bits of the PLS2. This value is constant during the entire duration of the current frame-group.

PLS2_NEXT_AP_MODE: This 2-bit field indicates whether additional parity is provided for PLS2 signaling in every frame of next frame-group. This value is constant during the entire duration of the current frame-group. The table 12 defines the
values of this field

PLS2_NEXT_AP_SIZE_CELL: This 15-bit field indicates the size (specified as the number of QAM cells) of the additional parity bits of the PLS2 in every frame of the next frame-group. This value is constant during the entire duration of the
current frame-group.

RESERVED: This 32-bit field is reserved for future use.

CRC_32: A 32-bit error detection code, which is applied to the entire PLS1 signaling.

FIG. 14 illustrates PLS2 data according to an embodiment of the present invention.

FIG. 14 illustrates PLS2-STAT data of the PLS2 data. The PLS2-STAT data are the same within a frame-group, while the PLS2-DYN data provide information that is specific for the current frame.

The details of fields of the PLS2-STAT data are as follows:

FIC_FLAG: This 1-bit field indicates whether the FIC is used in the current frame-group. If this field is set to `1`, the FIC is provided in the current frame. If this field set to `0`, the FIC is not carried in the current frame. This value
is constant during the entire duration of the current frame-group.

AUX_FLAG: This 1-bit field indicates whether the auxiliary stream(s) is used in the current frame-group. If this field is set to `1`, the auxiliary stream is provided in the current frame. If this field set to `0`, the auxiliary stream is not
carried in the current frame. This value is constant during the entire duration of current frame-group.

NUM_DP: This 6-bit field indicates the number of DPs carried within the current frame. The value of this field ranges from 1 to 64, and the number of DPs is NUM_DP+1.

DP_ID: This 6-bit field identifies uniquely a DP within a PHY profile.

DP_TYPE: This 3-bit field indicates the type of the DP. This is signaled according to the below table 13.

DP_GROUP_ID: This 8-bit field identifies the DP group with which the current DP is associated. This can be used by a receiver to access the DPs of the service components associated with a particular service, which will have the same
DP_GROUP_ID.

BASE_DP_ID: This 6-bit field indicates the DP carrying service signaling data (such as PSI/SI) used in the Management layer. The DP indicated by BASE_DP_ID may be either a normal DP carrying the service signaling data along with the service
data or a dedicated DP carrying only the service signaling data

DP_FEC_TYPE: This 2-bit field indicates the FEC type used by the associated DP. The FEC type is signaled according to the below table 14.

DP_TI_TYPE: This 1-bit field indicates the type of time-interleaving. A value of `0` indicates that one TI group corresponds to one frame and contains one or more TI-blocks. A value of `1` indicates that one TI group is carried in more than
one frame and contains only one TI-block.

DP_TI_LENGTH: The use of this 2-bit field (the allowed values are only 1, 2, 4, 8) is determined by the values set within the DP_TI_TYPE field as follows:

If the DP_TI_TYPE is set to the value `1`, this field indicates PI, the number of the frames to which each TI group is mapped, and there is one TI-block per TI group (NTI=1). The allowed PI values with 2-bit field are defined in the below table
18.

If the DP_TI_TYPE is set to the value `0`, this field indicates the number of TI-blocks NTI per TI group, and there is one TI group per frame (Pi=1). The allowed PI values with 2-bit field are defined in the below table 18.

DP_FRAME_INTERVAL: This 2-bit field indicates the frame interval (IJUMP) within the frame-group for the associated DP and the allowed values are 1, 2, 4, 8 (the corresponding 2-bit field is `00`, `01`, `10`, or `11`, respectively). For DPs that
do not appear every frame of the frame-group, the value of this field is equal to the interval between successive frames. For example, if a DP appears on the frames 1, 5, 9, 13, etc., this field is set to `4`. For DPs that appear in every frame, this
field is set to `1`.

DP_TI_BYPASS: This 1-bit field determines the availability of time interleaver 5050. If time interleaving is not used for a DP, it is set to `1`. Whereas if time interleaving is used it is set to `0`.

DP_FIRST_FRAME_IDX: This 5-bit field indicates the index of the first frame of the super-frame in which the current DP occurs. The value of DP_FIRST_FRAME_IDX ranges from 0 to 31

DP_NUM_BLOCK_MAX: This 10-bit field indicates the maximum value of DP_NUM_BLOCKS for this DP. The value of this field has the same range as DP_NUM_BLOCKS.

DP_PAYLOAD_TYPE: This 2-bit field indicates the type of the payload data carried by the given DP. DP_PAYLOAD_TYPE is signaled according to the below table 19.

DNP_MODE: This 2-bit field indicates the null-packet deletion mode used by the associated DP when DP_PAYLOAD_TYPE is set to TS (`00`). DNP_MODE is signaled according to the below table 23. If DP_PAYLOAD_TYPE is not TS (`00`), DNP_MODE is set
to the value `00`.

ISSY_MODE: This 2-bit field indicates the ISSY mode used by the associated DP when DP_PAYLOAD_TYPE is set to TS (`00`). The ISSY_MODE is signaled according to the below table 24 If DP_PAYLOAD_TYPE is not TS (`00`), ISSY_MODE is set to the value
`00`.

PID: This 13-bit field indicates the PID number for TS header compression when DP_PAYLOAD_TYPE is set to TS (`00`) and HC_MODE_TS is set to `01` or `10`.

RESERVED: This 8-bit field is reserved for future use.

The following field appears only if FIC_FLAG is equal to `1`:

FIC_VERSION: This 8-bit field indicates the version number of the FIC.

FIC_LENGTH_BYTE: This 13-bit field indicates the length, in bytes, of the FIC.

RESERVED: This 8-bit field is reserved for future use.

The following field appears only if AUX_FLAG is equal to `1`:

NUM_AUX: This 4-bit field indicates the number of auxiliary streams. Zero means no auxiliary streams are used.

AUX_CONFIG_RFU: This 8-bit field is reserved for future use.

AUX_STREAM_TYPE: This 4-bit is reserved for future use for indicating the type of the current auxiliary stream.

AUX_PRIVATE_CONFIG: This 28-bit field is reserved for future use for signaling auxiliary streams.

FIG. 15 illustrates PLS2 data according to another embodiment of the present invention.

FIG. 15 illustrates PLS2-DYN data of the PLS2 data. The values of the PLS2-DYN data may change during the duration of one frame-group, while the size of fields remains constant.

The details of fields of the PLS2-DYN data are as follows:

FRAME_INDEX: This 5-bit field indicates the frame index of the current frame within the super-frame. The index of the first frame of the super-frame is set to `0`.

PLS_CHANGE_COUNTER: This 4-bit field indicates the number of super-frames ahead where the configuration will change. The next super-frame with changes in the configuration is indicated by the value signaled within this field. If this field is
set to the value `0000`, it means that no scheduled change is foreseen: e.g., value `1` indicates that there is a change in the next super-frame.

FIC_CHANGE_COUNTER: This 4-bit field indicates the number of super-frames ahead where the configuration (i.e., the contents of the FIC) will change. The next super-frame with changes in the configuration is indicated by the value signaled
within this field. If this field is set to the value `0000`, it means that no scheduled change is foreseen: e.g. value `0001` indicates that there is a change in the next super-frame.

RESERVED: This 16-bit field is reserved for future use.

The following fields appear in the loop over NUM_DP, which describe the parameters associated with the DP carried in the current frame.

DP_ID: This 6-bit field indicates uniquely the DP within a PHY profile.

DP_START: This 15-bit (or 13-bit) field indicates the start position of the first of the DPs using the DPU addressing scheme. The DP_START field has differing length according to the PHY profile and FFT size as shown in the below table 27.

DP_NUM_BLOCK: This 10-bit field indicates the number of FEC blocks in the current TI group for the current DP. The value of DP_NUM_BLOCK ranges from 0 to 1023

RESERVED: This 8-bit field is reserved for future use.

The following fields indicate the FIC parameters associated with the EAC.

EAC_FLAG: This 1-bit field indicates the existence of the EAC in the current frame. This bit is the same value as the EAC_FLAG in the preamble.

EAS_WAKE_UP_VERSION_NUM: This 8-bit field indicates the version number of a wake-up indication.

If the EAC_FLAG field is equal to `1`, the following 12 bits are allocated for EAC_LENGTH_BYTE field. If the EAC_FLAG field is equal to `0`, the following 12 bits are allocated for EAC_COUNTER.

EAC_LENGTH_BYTE: This 12-bit field indicates the length, in byte, of the EAC.

EAC_COUNTER: This 12-bit field indicates the number of the frames before the frame where the EAC arrives.

The following field appears only if the AUX_FLAG field is equal to `1`:

AUX_PRIVATE_DYN: This 48-bit field is reserved for future use for signaling auxiliary streams. The meaning of this field depends on the value of AUX_STREAM_TYPE in the configurable PLS2-STAT.

CRC_32: A 32-bit error detection code, which is applied to the entire PLS2.

FIG. 16 illustrates a logical structure of a frame according to an embodiment of the present invention.

As above mentioned, the PLS, EAC, FIC, DPs, auxiliary streams and dummy cells are mapped into the active carriers of the OFDM symbols in the frame. The PLS1 and PLS2 are first mapped into one or more FSS(s). After that, EAC cells, if any, are
mapped immediately following the PLS field, followed next by FIC cells, if any. The DPs are mapped next after the PLS or EAC, FIC, if any. Type 1 DPs follows first, and Type 2 DPs next. The details of a type of the DP will be described later. In some
case, DPs may carry some special data for EAS or service signaling data. The auxiliary stream or streams, if any, follow the DPs, which in turn are followed by dummy cells. Mapping them all together in the above mentioned order, i.e. PLS, EAC, FIC,
DPs, auxiliary streams and dummy data cells exactly fill the cell capacity in the frame.

FIG. 17 illustrates PLS mapping according to an embodiment of the present invention.

PLS cells are mapped to the active carriers of FSS(s). Depending on the number of cells occupied by PLS, one or more symbols are designated as FSS(s), and the number of FSS(s) N_FSS is signaled by NUM_FSS in PLS1. The FSS is a special symbol
for carrying PLS cells. Since robustness and latency are critical issues in the PLS, the FSS(s) has higher density of pilots allowing fast synchronization and frequency-only interpolation within the FSS.

PLS cells are mapped to active carriers of the NFSS FSS(s) in a top-down manner as shown in an example in FIG. 17. The PLS1 cells are mapped first from the first cell of the first FSS in an increasing order of the cell index. The PLS2 cells
follow immediately after the last cell of the PLS1 and mapping continues downward until the last cell index of the first FSS. If the total number of required PLS cells exceeds the number of active carriers of one FSS, mapping proceeds to the next FSS
and continues in exactly the same manner as the first FSS.

After PLS mapping is completed, DPs are carried next. If EAC, FIC or both are present in the current frame, they are placed between PLS and "normal" DPs.

FIG. 18 illustrates EAC mapping according to an embodiment of the present invention.

EAC is a dedicated channel for carrying EAS messages and links to the DPs for EAS. EAS support is provided but EAC itself may or may not be present in every frame. EAC, if any, is mapped immediately after the PLS2 cells. EAC is not preceded
by any of the FIC, DPs, auxiliary streams or dummy cells other than the PLS cells. The procedure of mapping the EAC cells is exactly the same as that of the PLS.

The EAC cells are mapped from the next cell of the PLS2 in increasing order of the cell index as shown in the example in FIG. 18. Depending on the EAS message size, EAC cells may occupy a few symbols, as shown in FIG. 18.

EAC cells follow immediately after the last cell of the PLS2, and mapping continues downward until the last cell index of the last FSS. If the total number of required EAC cells exceeds the number of remaining active carriers of the last FSS
mapping proceeds to the next symbol and continues in exactly the same manner as FSS(s). The next symbol for mapping in this case is the normal data symbol, which has more active carriers than a FSS.

After EAC mapping is completed, the FIC is carried next, if any exists. If FIC is not transmitted (as signaled in the PLS2 field), DPs follow immediately after the last cell of the EAC.

FIG. 19 illustrates FIC mapping according to an embodiment of the present invention.

(a) shows an example mapping of FIC cell without EAC and (b) shows an example mapping of FIC cell with EAC.

FIC is a dedicated channel for carrying cross-layer information to enable fast service acquisition and channel scanning. This information primarily includes channel binding information between DPs and the services of each broadcaster. For fast
scan, a receiver can decode FIC and obtain information such as broadcaster ID, number of services, and BASE_DP_ID. For fast service acquisition, in addition to FIC, base DP can be decoded using BASE_DP_ID. Other than the content it carries, a base DP
is encoded and mapped to a frame in exactly the same way as a normal DP. Therefore, no additional description is required for a base DP. The FIC data is generated and consumed in the Management Layer. The content of FIC data is as described in the
Management Layer specification.

The FIC data is optional and the use of FIC is signaled by the FIC_FLAG parameter in the static part of the PLS2 . If FIC is used, FIC_FLAG is set to `1` and the signaling field for FIC is defined in the static part of PLS2 . Signaled in this
field are FIC_VERSION, and FIC_LENGTH_BYTE. FIC uses the same modulation, coding and time interleaving parameters as PLS2. FIC shares the same signaling parameters such as PLS2_MOD and PLS2_FEC. FIC data, if any, is mapped immediately after PLS2 or
EAC if any. FIC is not preceded by any normal DPs, auxiliary streams or dummy cells. The method of mapping FIC cells is exactly the same as that of EAC which is again the same as PLS.

Without EAC after PLS, FIC cells are mapped from the next cell of the PLS2 in an increasing order of the cell index as shown in an example in (a). Depending on the FIC data size, FIC cells may be mapped over a few symbols, as shown in (b).

FIC cells follow immediately after the last cell of the PLS2, and mapping continues downward until the last cell index of the last FSS. If the total number of required

FIC cells exceeds the number of remaining active carriers of the last FSS, mapping proceeds to the next symbol and continues in exactly the same manner as FSS(s). The next symbol for mapping in this case is the normal data symbol which has more
active carriers than a FSS.

If EAS messages are transmitted in the current frame, EAC precedes FIC, and FIC cells are mapped from the next cell of the EAC in an increasing order of the cell index as shown in (b).

After FIC mapping is completed, one or more DPs are mapped, followed by auxiliary streams, if any, and dummy cells.

FIG. 20 illustrates a type of DP according to an embodiment of the present invention.

shows type 1 DP and (b) shows type 2 DP.

After the preceding channels, i.e., PLS, EAC and FIC, are mapped, cells of the DPs are mapped. A DP is categorized into one of two types according to mapping method:

Type 1 DP: DP is mapped by TDM

Type 2 DP: DP is mapped by FDM

The type of DP is indicated by DP_TYPE field in the static part of PLS2 . FIG. 20 illustrates the mapping orders of Type 1 DPs and Type 2 DPs. Type 1 DPs are first mapped in the increasing order of cell index, and then after reaching the last
cell index, the symbol index is increased by one. Within the next symbol, the DP continues to be mapped in the increasing order of cell index starting from p=0. With a number of DPs mapped together in one frame, each of the Type 1 DPs are grouped in
time, similar to TDM multiplexing of DPs.

Type 2 DPs are first mapped in the increasing order of symbol index, and then after reaching the last OFDM symbol of the frame, the cell index increases by one and the symbol index rolls back to the first available symbol and then increases from
that symbol index. After mapping a number of DPs together in one frame, each of the Type 2 DPs are grouped in frequency together, similar to FDM multiplexing of DPs.

Type 1 DPs and Type 2 DPs can coexist in a frame if needed with one restriction; Type 1 DPs always precede Type 2 DPs. The total number of OFDM cells carrying Type 1 and Type 2 DPs cannot exceed the total number of OFDM cells available for
transmission of DPs: D.sub.DP1+D.sub.DP2.ltoreq.D.sub.DP [Math figure 2]

where DDP1 is the number of OFDM cells occupied by Type 1 DPs, DDP2 is the number of cells occupied by Type 2 DPs. Since PLS, EAC, FIC are all mapped in the same way as Type 1 DP, they all follow "Type 1 mapping rule". Hence, overall, Type 1
mapping always precedes Type 2 mapping.

FIG. 21 illustrates DP mapping according to an embodiment of the present invention.

shows an addressing of OFDM cells for mapping type 1 DPs and (b) shows an addressing of OFDM cells for mapping for type 2 DPs.

The addressing scheme defines the order in which the cells from the TIs for each of the Type 1 DPs are allocated to the active data cells. It is also used to signal the locations of the DPs in the dynamic part of the PLS2.

Without EAC and FIC, address 0 refers to the cell immediately following the last cell carrying PLS in the last FSS. If EAC is transmitted and FIC is not in the corresponding frame, address 0 refers to the cell immediately following the last
cell carrying EAC. If FIC is transmitted in the corresponding frame, address 0 refers to the cell immediately following the last cell carrying FIC. Address 0 for Type 1 DPs can be calculated considering two different cases as shown in (a). In the
example in (a), PLS, EAC and FIC are assumed to be all transmitted. Extension to the cases where either or both of EAC and FIC are omitted is straightforward. If there are remaining cells in the FSS after mapping all the cells up to FIC as shown on the
left side of (a).

Addressing of OFDM cells for mapping Type 2 DPs (0, . . . , DDP2-1) is defined for the active data cells of Type 2 DPs. The addressing scheme defines the order in which the cells from the TIs for each of the Type 2 DPs are allocated to the
active data cells. It is also used to signal the locations of the DPs in the dynamic part of the PLS2.

Three slightly different cases are possible as shown in (b). For the first case shown on the left side of (b), cells in the last FSS are available for Type 2 DP mapping. For the second case shown in the middle, FIC occupies cells of a normal
symbol, but the number of FIC cells on that symbol is not larger than CFSS. The third case, shown on the right side in (b), is the same as the second case except that the number of FIC cells mapped on that symbol exceeds CFSS.

The extension to the case where Type 1 DP(s) precede Type 2 DP(s) is straightforward since PLS, EAC and FIC follow the same "Type 1 mapping rule" as the Type 1 DP(s).

A data pipe unit (DPU) is a basic unit for allocating data cells to a DP in a frame.

A DPU is defined as a signaling unit for locating DPs in a frame. A Cell Mapper 7010 may map the cells produced by the TIs for each of the DPs. A Time interleaver 5050 outputs a series of TI-blocks and each TI-block comprises a variable number
of XFECBLOCKs which is in turn composed of a set of cells. The number of cells in an XFECBLOCK, Ncells, is dependent on the FECBLOCK size, Nldpc, and the number of transmitted bits per constellation symbol. A DPU is defined as the greatest common
divisor of all possible values of the number of cells in a XFECBLOCK, Ncells, supported in a given PHY profile. The length of a DPU in cells is defined as LDPU. Since each PHY profile supports different combinations of FECBLOCK size and a different
number of bits per constellation symbol, LDPU is defined on a PHY profile basis.

FIG. 22 illustrates an FEC structure according to an embodiment of the present invention.

FIG. 22 illustrates an FEC structure according to an embodiment of the present invention before bit interleaving. As above mentioned, Data FEC encoder may perform the FEC encoding on the input BBF to generate FECBLOCK procedure using outer
coding (BCH), and inner coding (LDPC). The illustrated FEC structure corresponds to the FECBLOCK. Also, the FECBLOCK and the FEC structure have same value corresponding to a length of LDPC codeword.

The BCH encoding is applied to each BBF (Kbch bits), and then LDPC encoding is applied to BCH-encoded BBF (Kldpc bits=Nbch bits) as illustrated in FIG. 22.

The value of Nldpc is either 64800 bits (long FECBLOCK) or 16200 bits (short FECBLOCK).

The below table 28 and table 29 show FEC encoding parameters for a long FECBLOCK and a short FECBLOCK, respectively.

2) Accumulate the first information bit--i0, at parity bit addresses specified in the first row of an addresses of parity check matrix. The details of addresses of parity check matrix will be described later. For example, for rate 13/15:
p.sub.983=p.sub.983.sym.i.sub.0 p.sub.2815=p.sub.2815.sym.i.sub.0 p.sub.4837=p.sub.4837.sym.i.sub.0 p.sub.4989=p.sub.4989.sym.i.sub.0 p.sub.6138=p.sub.6138.sym.i.sub.0 p.sub.6458=p.sub.6458.sym.i.sub.0 p.sub.6921=p.sub.6921.sym.i.sub.0
p.sub.6974=p.sub.6974.sym.i.sub.0 p.sub.7572=p.sub.7572.sym.i.sub.0 p.sub.8260=p.sub.8260.sym.i.sub.0 p.sub.8496=p.sub.8496.sym.i.sub.0 [Math figure 5]

where x denotes the address of the parity bit accumulator corresponding to the first bit i0, and Qldpc is a code rate dependent constant specified in the addresses of parity check matrix. Continuing with the example, Qldpc=24 for rate 13/15, so
for information bit i1, the following operations are performed: p.sub.1007=p.sub.1007.sym.i.sub.1 p.sub.2839=p.sub.2839.sym.i.sub.1 p.sub.4861=p.sub.4861.sym.i.sub.1 p.sub.5013=p.sub.5013.sym.i.sub.1 p.sub.6162=p.sub.6162.sym.i.sub.1
p.sub.6482=p.sub.6482.sym.i.sub.1 p.sub.6945=p.sub.6945.sym.i.sub.1 p.sub.6998=p.sub.6998.sym.i.sub.1 p.sub.7596=p.sub.7596.sym.i.sub.1 p.sub.8284=p.sub.8284.sym.i.sub.1 p.sub.8520=p.sub.8520.sym.i.sub.1 [Math figure 7]

4) For the 361st information bit i360, the addresses of the parity bit accumulators are given in the second row of the addresses of parity check matrix. In a similar manner the addresses of the parity bit accumulators for the following 359
information bits is, s=361, 362, . . . , 719 are obtained using the Math figure 6, where x denotes the address of the parity bit accumulator corresponding to the information bit i360, i.e., the entries in the second row of the addresses of parity check
matrix.

5) In a similar manner, for every group of 360 new information bits, a new row from addresses of parity check matrixes used to find the addresses of the parity bit accumulators.

After all of the information bits are exhausted, the final parity bits are obtained as follows:

This LDPC encoding procedure for a short FECBLOCK is in accordance with t LDPC encoding procedure for the long FECBLOCK, except replacing the table 30 with table 31, and replacing the addresses of parity check matrix for the long FECBLOCK with
the addresses of parity check matrix for the short FECBLOCK.

The FECBLOCK may be parity interleaved. At the output of the parity interleaving, the LDPC codeword consists of 180 adjacent QC blocks in a long FECBLOCK and 45 adjacent QC blocks in a short FECBLOCK. Each QC block in either a long or short
FECBLOCK consists of 360 bits. The parity interleaved LDPC codeword is interleaved by QCB interleaving. The unit of QCB interleaving is a QC block. The QC blocks at the output of parity interleaving are permutated by QCB interleaving as illustrated in
FIG. 23, where Ncells=64800/.eta. mod or 16200/.eta. mod according to the FECBLOCK length. The QCB interleaving pattern is unique to each combination of modulation type and LDPC code rate.

After QCB interleaving, inner-group interleaving is performed according to modulation type and order (.eta. mod) which is defined in the below table 32. The number of QC blocks for one inner-group, NQCB_IG, is also defined.

The inner-group interleaving process is performed with NQCB_IG QC blocks of the QCB interleaving output. Inner-group interleaving has a process of writing and reading the bits of the inner-group using 360 columns and NQCB_IG rows. In the write
operation, the bits from the QCB interleaving output are written row-wise. The read operation is performed column-wise to read out m bits from each row, where m is equal to 1 for NUC and 2 for NUQ.

FIG. 24 illustrates a cell-word demultiplexing according to an embodiment of the present invention.

shows a cell-word demultiplexing for 8 and 12 bpcu MIMO and (b) shows a cell-word demultiplexing for 10 bpcu MIMO.

FIG. 25 illustrates a time interleaving according to an embodiment of the present invention.

(a) to (c) show examples of TI mode.

The time interleaver operates at the DP level. The parameters of time interleaving (TI) may be set differently for each DP.

The following parameters, which appear in part of the PLS2-STAT data, configure the TI:

DP_TI_TYPE (allowed values: 0 or 1): Represents the TI mode; `0` indicates the mode with multiple TI blocks (more than one TI block) per TI group. In this case, one TI group is directly mapped to one frame (no inter-frame interleaving). `1`
indicates the mode with only one TI block per TI group. In this case, the TI block may be spread over more than one frame (inter-frame interleaving).

DP_TI_LENGTH: If DP_TI_TYPE=`0`, this parameter is the number of TI blocks NTI per TI group. For DP_TI_TYPE=`1`, this parameter is the number of frames PI spread from one TI group.

DP_NUM_BLOCK_MAX (allowed values: 0 to 1023): Represents the maximum number of XFECBLOCKs per TI group.

DP_FRAME_INTERVAL (allowed values: 1, 2, 4, 8): Represents the number of the frames IJUMP between two successive frames carrying the same DP of a given PHY profile.

DP_TI_BYPASS (allowed values: 0 or 1): If time interleaving is not used for a DP, this parameter is set to `1`. It is set to `0` if time interleaving is used.

Additionally, the parameter DP_NUM_BLOCK from the PLS2-DYN data is used to represent the number of XFECBLOCKs carried by one TI group of the DP.

When time interleaving is not used for a DP, the following TI group, time interleaving operation, and TI mode are not considered. However, the Delay Compensation block for the dynamic configuration information from the scheduler will still be
required. In each DP, the XFECBLOCKs received from the SSD/MIMO encoding are grouped into TI groups. That is, each TI group is a set of an integer number of XFECBLOCKs and will contain a dynamically variable number of XFECBLOCKs. The number of
XFECBLOCKs in the TI group of index n is denoted by N.times.BLOCK_Group (n) and is signaled as DP_NUM_BLOCK in the PLS2-DYN data. Note that N.times.BLOCK_Group(n) may vary from the minimum value of 0 to the maximum value N.times.BLOCK_Group_MAX
(corresponding to DP_NUM_BLOCK_MAX) of which the largest value is 1023.

Each TI group is either mapped directly onto one frame or spread over PI frames. Each TI group is also divided into more than one TI blocks (NTI), where each TI block corresponds to one usage of time interleaver memory. The TI blocks within
the TI group may contain slightly different numbers of XFECBLOCKs. If the TI group is divided into multiple TI blocks, it is directly mapped to only one frame. There are three options for time interleaving (except the extra option of skipping the time
interleaving) as shown in the below table 33.

TABLE-US-00033 TABLE 33 Mode Description Option- Each TI group contains one TI block and is mapped directly 1 to one frame as shown in (a). This option is signaled in the PLS2-STAT by DP_TI_TYPE = `0` and DP_TI_LENGTH = `1` (N.sub.TI = 1).
Option- Each TI group contains one TI block and is mapped to more 2 than one frame. (b) shows an example, where one TI group is mapped to two frames, i.e., DP_TI_LENGTH = `2` (P.sub.I = 2) and DP_FRAME_INTERVAL (I.sub.JUMP = 2). This provides greater
time diversity for low data-rate services. This option is signaled in the PLS2-STAT by DP_TI_TYPE = `1`. Option- Each TI group is divided into multiple TI blocks and is mapped 3 directly to one frame as shown in (c). Each TI block may use full TI
memory, so as to provide the maximum bit-rate for a DP. This option is signaled in the PLS2-STAT signaling by DP_TI_TYPE = `0` and DP_TI_LENGTH = NTI, while P.sub.I = 1.

In each DP, the TI memory stores the input XFECBLOCKs (output XFECBLOCKs from the SSD/MIMO encoding block). Assume that input XFECBLOCKs are defined as (d.sub.n,s,0,0,d.sub.n,s,0,1, . . . ,d.sub.n,s,0,N.sub.cells.sub.-1,d.sub.n,s,1,0, . . .
,d.sub.n,s,0,N.sub.cells.sub.-1, . . . ,d.sub.n,s,N.sub.xBLOCK--TI.sub.(n,s)-1,0, . . . ,d.sub.n,s,N.sub.xBLOCK--TI.sub.(n,s)-1,N.sub.cells.sub.-1), where d.sub.n,s,r,q is the qth cell of the rth XFECBLOCK in the sth TI block of the nth TI group and
represents the outputs of SSD and MIMO encodings as follows

Typically, the time interleaver will also act as a buffer for DP data prior to the process of frame building. This is achieved by means of two memory banks for each DP. The first TI-block is written to the first bank. The second TI-block is
written to the second bank while the first bank is being read from and so on.

The TI is a twisted row-column block interleaver. For the sth TI block of the nth TI group, the number of rows N.sub.r of a TI memory is equal to the number of cells N.sub.cells, i.e., N.sub.r=N.sub.cells while the number of columns N.sub.c is
equal to the number N.sub.xBLOCK.sub._.sub.TI(n,s)

Hereinafter, the input formatting module/step and output formatting module/step in the method of transmitting and receiving a broadcast signal described above will be described additionally.

As described above with reference to FIG. 1, the input formatting module of the broadcast transmitter may demultiplex an input stream to at least one data pipe (DP) and the input stream may be input as IP streams/packets, MPEG-2 TS, or a type of
generic stream. Also, as illustrated in FIGS. 2 through 4, the input formatting module may include a mode adaptation module and a stream adaptation module. As illustrated in FIGS. 2 and 3, the mode adaptation module slices input data stream and insert
the same to a data field of a baseband (BB) frame. Hereinafter, operations of a broadcast signal transmitter and a broadcast signal receiver in a case in which input and output streams are IP streams will be described. In the present disclosure, the
broadcast signal transmitter may also be referred to as a broadcast transmitter or a broadcast signal transmission apparatus and the broadcast signal receiver may also be referred to as a broadcast receiver or a broadcast signal reception apparatus.

FIG. 26 is a view illustrating a mode adaptation module of a broadcast signal transmitter according to an embodiment of the present invention.

The mode adaptation module of FIG. 26 is included in the input formatting module of FIG. 1, and is another embodiment of the mode adaptation module illustrated in FIGS. 2 and 3.

The mode adaptation module of FIG. 26 processes a multi-input stream, and as illustrated in FIGS. 2 and 3 described above, the mode adaptation module of FIG. 26 slices an incoming data stream and inserts the same to a data field of a baseband
frame. Blocks and modules corresponding to the blocks and modules described above with reference to FIGS. 2 and 3 will be described briefly.

A preprocessing module 26010 may also be referred to as an input stream splitter module and split an input data stream into multiple services or service components. An input interface module 26020 may map input data to an internal logical-bit
format. An input stream synchronizer module 26030 may also be referred to as an ISSY, and provides a means (ISSY information) guaranteeing a constant bit rate (CBR) and a constant end-to-end transmission delay. A compensating delay module 26040 can
delay the split TS packet stream following the insertion of ISSY information to allow a TS packet recombining mechanism without requiring additional memory in the receiver. A null packet deletion module 26060 is used only for the TS input stream case.
In FIG. 26, the input interface module 26020 and other dotted lined modules 26030, 26040, and 26060 may be used when an input stream is a TS stream, and may be omitted or input data may be bypassed when an IP stream/IP packet is processed as in the
present invention.

As described above, the header compression module 26050 may perform packet header compression to increase transmission efficiency with respect to an IP input stream. In particular, the header compression module 26050 may use a technique of
compressing a plurality of IP headers, and this will be described in detail hereinafter.

A BB frame header insertion module 26070 may insert a BB frame header to a front end of a BB frame. In FIG. 26, the BB frame header insertion module 26070 may also play the role of the BB frame slicer 3060 of FIG. 3. However, according to
embodiments, the BB frame slicer may be separately provided, and in this case, the BB frame slicer may allocate data of IP packets to payload of a BB frame, and the BB frame header insertion module 26070 may insert a BB frame header in front of payload
of the BB frame. In the present invention, the BB frame header insertion module 26070 may insert information related to IP header compression (IP header compression information) used in the header compression module 26050 into a BB frame header, and the
IP header compression information may be inserted into an extension field of the BB frame header. This will be described in more detail hereinafter.

The BB frame header may also be referred to as a BB frame header part. The BB frame header or the BB frame header part is a data part in front of payload in a BB frame. According to embodiments, an essential portion of the BB frame header part
may be referred to as a BB frame header, but in this disclosure, the BB frame header may refer to the data part in front of payload of a BB frame. Also, hereinafter, an IP packet may be referred to as a packet, and an IP packet header may be referred to
as a packet header.

FIG. 27 is a view illustrating an output processor module of the broadcast signal receiver according to an embodiment of the present invention.

The output processor module of FIG. 27 may correspond to the output processor module 9030 of the broadcast signal receiver of FIG. 9.

The output processor module may include at least one among a BB frame header parser module 27010, a null packet insertion module 27020, a header de-compression module 27030, a di-jitter buffer module 27040, a packet recombining module 27050, and
a TS clock regeneration module 27060. In particular, the null packet insertion module 27020, the di-jitter buffer module 27040, and the TS clock regeneration module 27060 may be omitted or bypass reception data in case of processing an IP stream/IP
packet.

The BB frame header parser module 27010 may parse data of a header part included in a BB frame to obtain various types of signaling information. In the present invention, the BB frame header parser module 27010 parses a BB frame header to
obtain IP header compression information included in an extension field.

The packet recombining module 27050 may combine IP packets to output an IP stream. The IP stream may be recovered in units of service so as to be output.

FIG. 28 is a view illustrating an IP header compression method according to an embodiment of the present invention.

The broadcast transmitter may compress an IP header by using a plurality of methods. For example, header compression techniques such as a header compression for broadcasting (HCfB) method, a U-mode method of robust header compression (ROHC),
and the like, may be used. With these methods, in case of a stream in which IP fields, excluding a packet length, are the same, IP packets may be compressed by using a scheme in which full IP header information is sent once for the first time and only
changed values are transmitted in the IP header in subsequent IP streams.

As illustrated in FIG. 28, for IP packets following the IP packet having a full header, only information different from the full header may be transmitted as a partial header, thereby reducing signaling overhead.

For example, in a case in which an input stream is an IPv4/UDP stream, an IP packet has an IP header of a total of 28 bytes. In case of compressing the header by using the HCfB method, a full header may be compressed to 23 bytes and a partial
header may be compressed to 5 bytes. In a case in which an input stream is an IPv6/UDP stream, an IP packet has an IP header of a total of 48 bytes. In case of compressing by using the HCfB method, a full header may be compressed to 45 bytes and a
partial header may be compressed to 3 bytes.

The compressed headers do not include packet length information, and the packet length information may be transmitted through an additional encapsulation header using an encapsulation scheme. In other words, an encapsulation header including
header compression (HC) information is added to each of the compressed IP packets, and the header compression information may include length information of the IP packets.

In another example, an integrated service digital broadcasting-terrestrial (ISDB-T) system uses a type length value (TLV) scheme as a compression method, and signals a packet length by using a 4-byte TLV header. Also, in this scheme, 4-byte
encapsulation header exists in front of every compressed packet.

In case of an embodiment in which packet length information is signaled through a separate additional header, while compressing an IP packet header, signaling overhead occurs and processing of packets may not be effective. Thus, the present
invention proposes another method in conjunction therewith.

FIG. 29 is a view illustrating an IP header compression method according to another embodiment of the present invention.

Referring to FIG. 29, a scheme of using an extension field of a BB frame, rather than the foregoing encapsulation scheme, is proposed as a scheme of transmitting header compression information of an IP packet in an IP direct transmission scheme.

In FIG. 29, the broadcast transmitter may compress IP packets in the manner as that of the method described above with reference to FIG. 28. In this embodiment, however, the broadcast transmitter uses a method of signaling IP header compression
information by inserting it into a header of a BB frame, rather than signaling the IP header compression information as a separate additional header through encapsulation.

The IP header compression information signaled in a header of a BB frame may include at least one of a start position of an IP packet, an IP header compression scheme, or a packet type. A start position of an IP packet may be signaled in a BB
frame or may be signaled as an IP packet length such that a position can be known by using a length of IP packets. The IP header compression information may also be referred to as header compression information in this disclosure, and hereinafter, an
embodiment of a method of signaling header compression information will be described additionally.

FIG. 30 is a view illustrating a method of signaling compression information according to an embodiment of the present invention.

In the embodiment of FIG. 30, a BB frame header may include at least one of a STUFFI field, a SYNCD field, an EXTI field, an RFU field, or an Extension field. However, according to embodiments, the configuration of the BB frame header and order
of the fields may be altered.

The STUFFI field describes whether the stuffing field is or is not within the BBF. If STUFFI=`0`, the BBF does not include the stuffing field and the in-band signaling field. Otherwise, the BBF has the stuffing field or the in-band signaling
field.

The SYNCD field describes the distance in bytes from the beginning of the data field to the beginning of the first transmitted UP that starts in the data field. SYNCD=0_D means that the first UP is aligned to the beginning of the data field.
SYNCD=8191_D means that no UPs starts in the data field.

The RFU (1-bits) field is reserved for future use. In this embodiment, 2-bit RFU field is changed to 1-bit RFU field and 1 bit is allocated to an EXTI field.

The EXTI field indicates whether an extension field exists.

In a case in which an extension field is used to signal IP header compression information as described above, the extension field may be configured as shown in Table 34 of FIG. 30. Table 34 shows an embodiment of syntax of an extension
field/table for transmitting IP header compression information, and a specific syntax and the number of allocated bits are not limited thereto.

Descriptions of the fields included in Table 34 are as follows.

extension_type field is a field distinguishing the purpose of an extension field and may be set to a type regarding header compression.

header_compression_mode indicates an IP header compressions scheme in use. For example, it may indicate the foregoing HCfB scheme, the U-mode scheme of RoHC, and the like.

num_ip_packet may indicate the number (N) of IP packet headers included in a corresponding BB frame. This field has N number of packet_type fields and packet_start_position fields.

packet_type indicates a type of a compressed IP packet and may be configured as illustrated in Table 35.

Thereafter, in order to align a final field length by byte, a reserved (0 to 7 bits) may be included.

Finally, a CRC may be inserted to perform an error check function of the extension field.

Table 35 describes a packet_type field.

A field value 000 indicates that a header of a compressed packet is a full IP header. Namely, the field value 000 is used when a compressed IP packet/header is a newly defined full IP header without having a common compression ID (CID) such as
a partial packet which is previously transmitted. Such a header may be referred to as a new full IP header.

A field value 001 indicates that a compressed packet header is a full IP header. Namely, the field value 001 is used when a compressed IP packet/header has the same CID as that of a previously transmitted partial packet. Such a header may be
referred to as a continuous full IP header.

A field value 010 is used when a header of a compressed packet is a partial IP header.

A field value 111 is used to transmit information assisting IP header compression.

Other remaining fields may be used as reserved fields that may be added later.

The packet_type field will be described in addition, and a full IP header may be transmitted a plurality of times in order to decode partial headers of a plurality of subsequent IP packets. For example, full IP headers may be transmitted at
predetermined intervals to ensure efficiency of decoding, as well as for a case in which contents of an IP header is changed. The full IP headers which are not changed in contents and repeatedly transmitted may be identified by the field value 001. In
a case in which the packet_type field value is 000, an IP full header as a new one may be used to recover information of subsequent partial headers, and in a case in which the field value is 001, the IP full header, as a repeated one, may be used to
recover information of subsequent partial headers and preceding partial headers.

FIG. 31 is a view illustrating a method for signaling header compression information according to another embodiment of the present invention.

Also, in an embodiment of the present invention, a BB frame header may include a STUFFI field, a SYNCD field, an EXTI field, an RFU field, and an Extension field. However, according to embodiments, the configuration of the BB frame header and
order of fields may be altered. The BB frame header structure described above with reference to FIG. 30 and descriptions thereof will be omitted.

When an extension field is used to signal IP header compression information as described above, the extension field may be configured as shown in Table 36 of FIG. 31. Table 36 shows an embodiment of a syntax of an extension field/table for
transmitting IP header compression information, and a specific syntax and the number of allocated bits are not limited thereto. Table 36 shows a light version for reducing overhead, compared with Table 34.

Descriptions of the fields included in Table 36 are as follows.

packet_type (3 bits) field is a type of a compressed IP packet and may be configured like Table 35 of FIG. 30.

end_flag (1 bit) field is a field indicating whether a header is a final packet header in a BBA frame, by which a while loop may be terminated. If a field (ith field) is a final field, end_flag is set to 1 to have a CRC field. If there is a
(i+1)th field exists subsequently, the end_flag is set to 0 to have (i+1)th packet_type, end_flag, and packet_start_position field again.

packet_start_position field (13 bits) indicates a position in which a new packet starts, and may be signaled as an absolute position in a BB frame.

A unit is a byte unit, and 13 bits are allocated by a maximum of 8K bytes.

Thereafter, in order to align a final field length by byte, a reserved field (0 to 7 bits) is included.

Finally, a CRC is inserted to perform an error check function of the extension field.

In FIGS. 30 and 31, the method in which a position of a packet is signaled as a start point has been described. Hereinafter, a method in which a position of a packet is signaled by using a packet length will be described with reference to FIGS.
32 and 33

FIG. 32 is a view illustrating a method of signaling header compression information according to another embodiment of the present invention.

Also, in this embodiment, a BB frame header may include a STUFFI field, a SYNCD field, an EXTI field, an RFU field, and an Extension field. However, according to embodiments, the configuration of the BB frame header and order of fields may be
altered. The BB frame header structure described above with reference to FIG. 30 and descriptions thereof will be omitted.

When an extension field is used to signal IP header compression information as described above, the extension field may be configured as shown in Table 37 of FIG. 32. Table 37 shows an embodiment of a syntax of an extension field/table for
transmitting IP header compression information, and a specific syntax and the number of allocated bits are not limited thereto.

Descriptions of the fields included in Table 37 are as follows.

packet_type (2 bits) field is a type of a compressed IP packet and may be configured like Table 35 of FIG. 30.

end_flag (1 bit) field is a field indicating whether a header is a final packet header in a BBA frame, by which a while loop may be terminated. If a field (ith field) is a final field, end_flag is set to 1 to have a CRC field. If there is a
(i+1)th field exists subsequently, the end_flag is set to 0 to have (i+1)th packet_type, end_flag, and packet_length field again.

mtu_mode and packet_length are used to effectively express a corresponding packet length and implemented by using a variable mapping rule. mtu is a maximum transmission unit.

mtu_mode (1.about.4 bits) field serves to indicate a maximum value of a packet length, and accordingly, the number of allocated bits of a packet length is varied.

packet_length (11.about.16 bits) field indicates length information of a corresponding packet, and the number of allocated bits is varied according to mtu_mode.

Thereafter, in order to align a final field length by byte, a reserved field (0 to 7 bits) is included.

Finally, a CRC is inserted to perform an error check function of the extension field.

The packet_type table of Table 35 is as described above with reference to FIG. 30. Also, the foregoing table, an embodiment according to the TLV scheme, may be altered according to header compression schemes

FIG. 33 is a view illustrating an embodiment regarding a scheme of expressing a packet length.

As described above with reference to FIG. 32, in order to express a packet length by a minimum of bits, a mtu_mode field and a packet_length field having a variable field length may be used. In other words, in order to enhance transmission
efficiency, a packet length is divided into certain sections and signaling is performed according to a subtable.

Table 38 of FIG. 33 is a table illustrating field vales of the mtu_mode field according to lengths of an IP packet and packet_length field size corresponding thereto.

In a case in which a packet size is 4095 or smaller, the mtu_mode field is set to 0 as 1 bit, and thereafter, a packet size is indicated by using 12 bits in the packet_length field. In this case, the entire fields a total of 16 bits by adding
the packet_type (2 bits) and an end_flag (1 bit).

In a case in which the packet size ranges from 4096 to 8191, the mtu_mode field is set to 10 as 2 bits, and thereafter, a packet size is indicated by using 13 bits in the packet_length field. In this case, the entire fields a total of 18 bits
by adding the packet_type (2 bits) and the end_flag (1 bit).

In a case in which the packet size ranges from 8192 to 16383, the mtu_mode field is set to 110 as 3 bits, and thereafter, a packet size is indicated by using 14 bits in the packet_length field. In this case, the entire fields a total of 20 bits
by adding the packet_type (2 bits) and the end_flag (1 bit).

In a case in which the packet size ranges from 16384 to 32767, the mtu_mode field is set to 1110 as 4 bits, and thereafter, a packet size is indicated by using 15 bits in the packet_length field. In this case, the entire fields a total of 22
bits by adding the packet_type (2 bits) and the end_flag (1 bit).

In a case in which the packet size ranges from 32768 to 65535, the mtu_mode field is set to 11110 as 5 bits, and thereafter, a packet size is indicated by using 16 bits in the packet_length field. In this case, the entire fields have a total of
24 bits by adding the packet_type (2 bits) and the end_flag (1 bit).

In the case of using such a packet size representation scheme, an operation may be performed by the minimum packet capacity. However, in the encapsulation scheme described above, since the packet length is expressed by byte, and thus, 16 bits
may be expressed as 2 bytes, but in case of 18 bits, 3 bytes are required to express it, generating (byte alignment) overhead.

In contrast, in the embodiment of FIGS. 32 and 33, since they are continuously configured in the BB frame header, fields not formed by byte may be added and byte alignment may be finally performed only once, thus reducing overhead. In other
words, in the present invention, when information is allocated to the BB frame header, the information is allocated by bit unit, and fields not formed by byte, among the allocated information, are added to finally configure information by byte unit.

For example, three packets having a length of 2000 bytes are configured as in Case 1 of FIG. 33, three packets are configured by 2-byte fields through the proposed method, and in this case, a total of 6 bytes are required to describe the packet
length.

In contrast, in the encapsulation scheme described above, for example, in case of the TLV scheme, three encapsulation headers of 4 bytes per packet are required, requiring a total of 12 bytes. In the case of GSE, 6 bytes are finally required.

In a case in which three packets having lengths of 4100, 2200, and 4200 are included, the packets may be expressed as 2.25, 2, and 2.25 bytes, respectively, in the proposed method, and in order to align the packets by 8 bits, 4-bit reserved is
used, and thus, 7 bytes are finally required. In other words, since the packet lengths are expressed by 18 bits, 16 bits, and 18 bits in bit unit, respectively, and 4 bits are added, totaling 56 bits, and thus, when the bits are aligned as byte, 7 bytes
are obtained.

Meanwhile, in case of GSE, 26 bytes are required, and in case of TLV, 12 bytes are required.

In addition, among the fields collected in the BB frame header, an error check may be performed by using a CRC field.

In case of compressing a header of an IP packet, the encapsulation scheme of adding header compression information to each IP packet described above with reference to FIG. 288 or the scheme of including header compression information in a BB
frame header described above with reference to FIGS. 29 through 33 may be used. Hereinafter, the difference between the encapsulation scheme and the scheme proposed by the present invention will be described in detail.

FIG. 34 illustrates a configuration of a BB frame according to IP header compression methods according to an embodiment of the present invention.

As described above, a) in the encapsulation method, IP header compression information including packet length information is added as an encapsulation header to each IP packet, and b) in the proposed method, IP header compression information is
added as a table/field to a BB frame header.

In the encapsulation method, the encapsulation header is added to every IP packet, indicating length information of compressed IP packets. The length of the compressed IP packet may be expressed by a maximum of 16 bits, and in the TLV scheme, 4
bytes are fixedly used. In the case of GSE, a short IP packet has low overhead as 2 bytes, but as the IP packet length increases, a header may increase up to 59 bytes. Also, the encapsulation header should be operated by byte, and thus, it is difficult
to optimize transmission efficiency.

In contrast, however, in the proposed method, since a start point of each packet is pointed in a BB frame header, instead of transmitting a packet length, only a maximum of 13 bits to a minimum of 10 bits may be used according to code rates and
LDPC sizes. Also, in case of transmitting a packet length, required information may be signaled by a significantly smaller amount of data by using the mtu_mode field and Table 38. In addition, since every information is defined in the BB frame header,
alignment by byte may be performed once in the frame header unit, rather than by packet, minimizing overhead and facilitating function extension later.

FIG. 35 illustrates a method of configuring a BB frame according to IP header compression methods and an error checking method according to an embodiment of the present invention.

As illustrated in FIG. 35, a) in the case of the encapsulation method, if there is an error in a BB frame, it is not possible to check a location of an IP packet and it is difficult to check whether every IP packet has an error.

In contrast, b) in the proposed method, since header compression information including IP packet length information is transmitted in a header of a BB frame by applying a CRC technique, error detection capability is provided. Thus, as
illustrated in FIG. 35, even though a BB frame has an error, if there is no error in header compression information, a receiver can accurately know positions of IP packets. The receiver may use each IP packet by decoding header information and checking
an error by using internal check sum information.

In the case of the encapsulation method, even though only one of position information has an error as illustrated in FIG. 35, positions of all the subsequent packets may become uncertain due to a relative length of packets. However, in the case
of the proposed method, absolute positions of IP packets in a BB frame are signaled in the BB frame header, even though one position information has an error, there is no problem in recognizing positions of other IP packets, excluding the corresponding
IP packet, and obtaining IP header information.

FIG. 36 illustrates a configuration of a BB frame according to IP header compression methods and a packet access method according to an embodiment of the present invention.

As illustrated in FIG. 36, a) in the case of the encapsulation method, a receiver i) parses received BB frame header information, ii) parses an encapsulation header at a first IP packet position to obtain packet length information, and iii)
subsequently parses an encapsulation header of a next IP packet position. The receiver repeats this process to search for a full IP header, and when a full IP header is searched, the receiver may decode (or de-compress) a subsequent IP packet header by
using the full IP header.

In contrast, in the case of the proposed method, the receiver i) may parse received BB frame header information to obtain position information of a full IP header, and ii) decode (de-compress) an IP header at a corresponding position. Thus, the
rate of decompressing the IP packet header and the rate of decoding the IP packet can be significantly shortened.

In addition to the shortened decoding rate, a) in the case of the encapsulation method, it may happen that an encapsulation header of an IP packet included in a frame is not parsed. For example, an error may occur sporadically, and here, if an
error occurs in an encapsulation header position, the receiver may not be able to parse an IP packet even though the corresponding IP packet does not have an error. Thus, b) the proposed method can obtain the full IP header more safely and stably.

FIG. 37 illustrates a BB frame configuration and packet access method according to an embodiment of the present invention.

According to the proposed method, the receiver may obtain type information and position information of an IP packet header by parsing a BB frame header. In particular, when a full IP header is set to continue as described above, it means that a
CID value of a preceding partial IP header and a CID value of a subsequent full IP header are identical. Namely, when the full IP header set to continue is obtained, the preceding partial IP headers having the same CID may be decoded by using the
obtained full IP header, without having to search for the preceding full IP header, allowing for faster packet accessing.

FIG. 38 is a view illustrating a method for transmitting a broadcast signal according to an embodiment of the present invention.

Regarding a broadcast transmitter and an operation thereof, as described above, a broadcast signal transmitter may demultiplex an input stream into at least one data pipe (DP) by using an input formatting module (S38010). The broadcast
transmitter may perform error correction processing on data included in at least one DP by using a BICM module (S38020). The broadcast signal transmitter may map the data of the DP to a symbol of a signal frame to generate a signal frame including the
data of the DP, by using a frame building module (S38030). The broadcast signal transmitter may insert a preamble into a transmission signal and perform OFDM modulation thereon by using an OFDM generation module (S38040).

The broadcast transmitter may perform additional processing on an IP frame by using the input formatting module. Namely, the broadcast transmitter may compress IP packets included in an IP stream by using a header compression module, allocate
the IP packets to a BB frame by using a BB frame slicer module, and insert a BB frame header including IP header compression information into the BB frame by using a BB frame header insertion module.

As described above with reference to FIGS. 28 through 33, the broadcast transmitter may compress headers of IP packets included in an IP stream, and insert related IP header compression information into a BB frame header. The IP header
compression information may include IP packet position information, IP packet type information, and the like, and may be included in the BB frame header. The IP packet position information may be signaled as start position information of IP packets
within a signal frame as illustrated in FIGS. 30 and 31, or may be signaled as position information of the IP packets as illustrated in FIGS. 32 and 33. The IP header compression information includes various types of information as illustrated in the
Tables described above with reference to FIGS. 28 through 33, and may be included in various formats in the BB frame header. The IP header compression information may be included in an extension field of the BB frame header part, but the position of the
information may not be limited thereto.

FIG. 39 is a view illustrating a method for receiving a broadcast signal according to an embodiment of the present invention.

Regarding a broadcast receiver and an operation thereof, as described above, a broadcast signal receiver may perform signal detection and OFDM demodulation on a reception broadcast signal by using a synchronization/demodulation module (S39010).
The broadcast receiver may extract service data by parsing a signal frame of the reception broadcast signal by using a frame parsing module (S39020). The broadcast receiver may convert service data extracted from the reception broadcast signal into a
bit domain and perform deinterleaving thereon by using a demapping and decoding module (S39030). The broadcast receiver may output service data processed by using an output processing module, as a data stream (S39040).

The broadcast receiver may perform additional processing on an IP stream by using the output processing module. Namely, the broadcast receiver may obtain IP header compression information by parsing a BB frame header of the reception broadcast
signal by using a BB frame header parser module. The broadest receiver may de-compress headers of IP packets included in a BB frame by using the IP header compression information through a header de-compression module. The broadcast receiver may
combine IP packets by using a packet recombining module to output an IP stream.

As described above with reference to FIGS. 28 through 33, headers of the IP packets included in the IP stream are compressed, and the related IP header compression information may be included in the BB frame header. The IP header compression
information may include IP packet position information, IP packet type information, and the like. The IP packet position information may be signaled as start position information of IP packets within a signal frame as illustrated in FIGS. 30 and 31, or
may be signaled as position information of the IP packets as illustrated in FIGS. 32 and 33. The IP header compression information includes various types of information as illustrated in the Tables described above with reference to FIGS. 28 through 33,
and may be included in various formats in the BB frame header. The IP header compression information may be included in an extension field of the BB frame header part, but the position of the information may not be limited thereto.

In the specification, methods and apparatuses for receiving and transmitting a broadcast signal are used.

It will be appreciated by those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. Thus, it is intended that the present invention
covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Both apparatus and method inventions are mentioned in this specification and descriptions of both of the apparatus and method inventions may be complementarily applicable to each other.